After thinking about Kegan stages for years (see David Chapman's Developing ethical, social, and cognitive competence for a summary), I finally found a framing I really like. It is a framing of adaptations. It also explains how people can skip stages, or be at several stages at once, or seemingly perform every stage poorly. The answer is "yeah".
Kegan stages are adaptations to the society around you, and they oscillate from "focus on one" to "focus on many" and back. The framing of "subject", "object", etc is not necessary.
Just for kicks, we can extend this backwards:
Ignoring the imaginary stage 0 and the stage 1, I will describe stages 2–3–4–5 below, with some personal recollections. The spoiler is that I have failed every stage.
Warning: might be typical minding a lot here.
At stage 2, people around you are asocial. By "asocial" I mean that they don't play by any social rules. They are your parents (who are more like your masters than your friends) and your similarly asocial children peers. Nobody is keeping long-term track of anybody else's behavior. Your parents are not particularly accountable for how they treat you.
There is no variety. You have to adapt to your mother and father; maybe several siblings; male peers; female peers; and that's it. There aren't many identities that you need, and even the ones you will develop look more like behaviors than identities. (Example: quiet with your often-drunk dad, sweet with your mom, loud around the boys, showing off around the girls.)
Most importantly, everybody is either stuck with you anyway, or they can't give you anything you'd care about. Most things are provided by parents and peers.
In the conditions where only your short-term behavior counts, and where everybody else is asocial, you will behave asocially and tactically.
This adaptation is a skill. It can be developed well, or poorly. If people around you are so random that you can't deal with them even tactically, it will probably be developed poorly. If people around you are incredibly consistent and treat you absolutely the same way regardless of how you behave — i.e. you can't purposefully use them — the skill will also probably be developed poorly.
Now the personal section. There will be one for each stage.
I think that in my childhood, I got things regardless of how I behaved.
I know that I didn't interact with children much. I went to the kindergarten when I was five. My family was well-off, the kids around were poor; I had Plasticine at home and in the kindergarten we had cheese wax (literally). No opportunities for trade.
I could read by myself. I had my own room. I was the oldest child, and neither had to share, nor wanted anything my sister had.
All in all, I never learned to use people.
Update 23 Feb 2021: @jackinlondon objects:
I find it very difficult to relate your 2nd stage description to any memories I'd have from childhood, or what I see e.g. my cousins' young (3-8) children do when I visit. That seems off. Kids can definitely hold grudges, so it's hard to say they don't track behaviour.
I don't know what to do with this objection — it's pretty significant — so I'll just leave it here. An alternative theory might be needed.
At stage 3, people around you are social. They are keeping track of each other's behavior and identity, judging people based on that, and even judging people based on how those judge other people.
There is more variety. Everybody's got larger social networks. Everybody has years of [some kind of baggage] behind them. People have different skillsets.
Many things that you want are now possible to get from people who are not obligated to give them to you. Even things you want from your parents have become bigger, less certain, more dependent on your relationship with your parents. You will still be fed, but now you want a PlayStation.
God knows why, but some people have started to develop long-term relationships with each other that are not forced (unlike parent–child). You have also started meeting new people. First impressions turn out to matter a lot.
In these conditions, you have to start deceiving people strategically rather than tactically. Since people sometimes talk about you behind your back, you can't be a little psychopath anymore. When somebody new appears, you can present yourself entirely differently to them than you do to anybody else, but you have to figure it out on the fly.
Again, this adaptation is a skill — or rather a set of skills. If you don't have many people around you, or if they are inconsequential, you might not learn how to influence people long-term. If people never talk about you behind your back (or don't modify their behavior based on that), you won't learn to justify yourself, or pretend to be consistent. If you have increased emotional sensitivity (the underlying cause of ADHD?), you might not get a habit of asking for feedback. If you are naturally talented / rich / something (or if you are for whatever reason repulsive), you might be getting (or not getting) things regardless of how you exercise the social skills — and thus never train them.
Personally, I spent the whole middle and high school a) being vaguely liked by people around me because I was smart and well-off, b) not needing anything from people, c) not depending on favors academically, d) not in danger of being bullied, e) not interacting with almost anybody. Since I didn't have to pay attention to lessons, and really liked reading, I was just sitting and reading during every recess instead of socializing.
Until about 16, I didn't care about people. After 16, I got lonely and realized talking to people was fun — but I felt very bad about every rejection; didn't have any skills for coping with rejections; didn't know how to fix any obstacle in a relationship (even saying sorry was super hard); wasn't feeling close to my family; didn't have almost any school friends; at any moment had only one relationship and therefore couldn't find solace in the other relationships.
After finishing high school I went to study in a different country, then almost immediately dropped out of university, lived in a working class dormitory, and had a long-distance girlfriend whom I've only seen once for a week. I taught myself programming and found a remote job half a year after dropping out, with just one other person on the team.
Overall, between the ages 16 and 23 I had successfully avoided all long-term social groups that I could possibly care about. I never felt like I belonged anywhere. I was liked by a few people who were attracted to me — probably because I was smart, well-read, good with words, completely independent, reflective, free to travel, and free to spend any amount of time with them. I was also clinging to anybody who liked me, and emotionally affected by anybody who liked me.
Since all of this worked well for me, I didn't want to change any of it. I definitely didn't want to settle anywhere, because I thought I wouldn't be attractive to people who valued that I can spend any amount of time with them and move anywhere with them. I didn't want to become less vulnerable to rejection, because I thought it was an immensely attractive quality. Etc. In fact, I mistrusted anybody who didn't feel vulnerable about rejection and didn't seem to care about what I thought of them. Bonding over vulnerabilities was my way of socializing.
I ended up with just a slice of stage 3. I very much cared what people thought about me, and this is a stage 3 quality. However, when it came to "working" with more than one person at a time, my skills were completely missing. Same for maintaining any non-super-close relationships. Same for handling rejection. My solution was to double down on the skills that I already had — more traveling, more being interesting, more being awesome.
I found LessWrong and read it for several years. Since I was focusing on individuals and not groups, I wanted to be interesting much more than I wanted to belong; when a friend and I organized a LW meetup in Minsk, I introduced myself with "hi, I am actually contrarian about this whole thing". To normal people, I could be a rationalist, and to rationalists I could be a contrarian — interesting to people from both groups, killing both birds with one stone.
My life goals were: a girlfriend, and owning a Google-sized corporation. This is what I wrote down when a friend asked "what are your life goals?" once. Immortality was on the list as well, but it was out of reach, while a Google-sized corporation wasn't.
I don't know why exactly I wanted a Google-sized corporation. Perhaps so that it would protect me from rejection, and give some sense of achievement; since I didn't belong to any groups, I didn't have any idea that I could feel good by doing something good for a group; since I was only focusing on one relationship at a time, I didn't even consider that I might have or need or care about other friends if I already had a girlfriend.
At stage 4, people around you are in a system, or structure.
There are still friends and family and strangers, but there are two marked structures: who takes priority in personal relationships (e.g. partner > family > friends), and who takes priority at work (hierarchy). This is what you have to adapt to.
Stage 4 probably can't happen in a village, where everybody knows each other and everybody is in a single social network. It occurs when there are independent social networks — your boss doesn't care what your girlfriend says, so you have to decide who gets priority in what situations, and be able to justify yourself. It also occurs in networks that are too big (and therefore not social), or result-oriented (and therefore not social). Think of a factory rather than a community.
The skill of manipulating a single social network — e.g. getting people to like you by affecting other people in the network — is no longer sufficient when there is more than one network. Example: you were late to work because you had an obligation to your partner or family. If the social networks were united, it would excuse you (or else you would neglect the obligation! the society defines what is right!). However, the social networks are disjoint and therefore you are bad in the "work" network even though you are good in the "home" network.
The skill of manipulating a social network is also not sufficient when you are severely judged on anything other than how likable/etc you are. Work performance, athletic performance, doesn't matter.
In these conditions, two major skills develop.
Firstly, you learn to judge yourself (and others) by something other than social performance. Otherwise you would either feel bad because you "are" bad in one of the networks, or your non-social (e.g. work) responsibilities would suffer because you're trying to please people instead of working and making good decisions. This is described in Kegan stage 4 as a cope. Probably. I don't remember what I wrote there already.
Secondly, you learn that having rules or principles is useful for anything reality-tested. If you notice that you lose competitions unless you go to sleep early, you have to develop a powerful conviction that going to sleep early (instead of doing social things) is good, or else you will be losing competitions. If you notice that some of your teammates at work want to do things the way that reliably produces bad results, you want to be able to overrule them without breaking social ties or playing the game of "who's the most upset" constantly.
Moreover, and this is crucial: you don't want to become a social outcast, and therefore just saying "because I want to" is not enough. So, you learn to manipulate others by portraying what you think should be done as "what is right". To do that well, you have to be consistent and develop some model of "what is right".
Personally, until about 22 I thought I was at stage 4 — because I had very strong opinions about how things should be. When at the age of 19 I read about Kegan stages for the first time, I diagnosed myself as stage 4.
In reality, the only reason I was able to have strong opinions was that they never had to touch reality. For example, I loved libertarianism because I was indignant about military conscription and some other things — but I literally never was in a situation where this belief would change anything. I didn't vote even once in my life. I didn't have children. I didn't teach. I had employees for my side projects, but I was paying them out of my own pocket, and didn't care about my projects being on the verge of failure — or my money being misspent.
After finding Kegan and realizing that I was searching for ultimate truths and justifications, I also realized that there were no ultimate truths — that everything was arbitrary — and promptly fell into a two-weeks-long bout of nihilism, accompanied by "nothing matters, nothing matters" pulsating in my head.
I don't know why exactly I was obsessively searching for non-arbitrary truths. Maybe because I didn't have anything else to do. Maybe because I did argue with other philosophically-minded people a lot, particularly my dad, and so I had to justify my opinions even though I didn't have to follow them.
While my "home" structure was small, and my "work" structure was even smaller (a solo programmer, or working in a small team on standalone tasks), I didn't develop any skills for prioritizing home over work or the other way round. I also didn't develop any skills or principles for being good at work. Just writing code was enough.
Right now (25) I finally have enough home activities and work activities that I do have to prioritize. For example, I have decided that I am not going to work on Tuesdays and Thursdays and on the weekend. I have a work laptop and a home laptop, and I don't do work on the home laptop.
I also finally have a work project where a) I want to do well, and b) I have to have more principles in order to do well. This has been a huge boost. I have to make decisions, build a hierarchy, and adopt others' principles that I notice are working well.
So, I am learning stage 4 skills. I am also learning stage 3 and stage 2 skills (especially "being selfish and using people"), all at once.
At stage 5, there are many systems that you have to navigate.
If you don't ever encounter yourself in a situation where there are many diverse systems and you want or have to do well in each — you will probably not develop the stage 5 skillset. You will simply never have to.
If you do encounter yourself in a many-systems situation, you can no longer adopt a single set of principles. Any single set will serve you poorly in some systems.
At the same time, you can't abandon principles entirely, because you need principles to navigate any pair of systems. You can't say "I'll just do what you want" because it won't fly socially, and will also disrupt the important (real-world-important) stage 4 order inside some of the systems.
This forces you to develop a feel of which principles could work better in which systems. And you don't have the time to study each system entirely, so you might have to go with "yeah, people at project A seem to work better with more freedom and people at project B seem to work better in a strict hierarchy; I'll just use what works without worrying about which is 'ultimately right'".
I can't give good examples of what stage 5 looks like, but I think the major skill here is developing and using principles for each individual system you encounter. Examples of systems include: a family; a team, a department, a government; a certain area of your life, art / music / mathematics / anything else.
This skill has two prerequisites. Firstly, you have to not worry about doing this — not feel like you must adhere to a single set of principles. You have to be philosophically ready. Secondly, you have to have a feel of what your values are, and what you will even optimize when choosing the principles. You might have to look at your life and observe that some seemingly good things turn out to be unsatisfying in the long run. You might even have to accept that your values will become different later — you can probably predict some of the values you are slowly drifting towards but not there yet. You can no longer assume that you will remain constant.
Personally, when it comes to figuring out which principles work better for which systems — I haven't started at all.
I think I already feel like I don't have adhere to a single set of principles. The bout of nihilism was useful, after all.
And finally, I have very roughly accepted some of the values I have — progress of the humanity, self-expression, reducing suffering, diversity of what's happening around me. But I haven't completely accepted them and don't know the priority. What I know is that there are definitely more values out there, and can see some of them appearing in the future.
All of this suggests that parenting should not be the same at every stage of the child's life. I haven't ever been a parent, but let's see.
Taking stage 2 as an example — for the first time, I am convinced that you shouldn't treat a kid like an adult or a friend. This is because you want them to learn how to deal with predictable people without social memory. They will need this skill later in life, when dealing with situations where people are predictable and don't operate according to social rules. The simplest example is a waiter; if you don't want your child to feel like "shit what if the waiter doesn't like me", they should learn the skill of not thinking socially at all. And you will be a playground for developing that skill.
At stage 3, you can probably boost your child's development by providing feedback — "when you do X, it makes me feel Y" — while still remaining predictable. Why feedback? Because if your child is great at something, or really bad at something, or just weird, they might be getting very one-sided feedback from their peers. Without you, the child might be getting zero feedback about all the other sides. And without that feedback, they will have a very hard time figuring out how to manipulate social networks where every their act is influencing something.
At stage 4, you probably need to disengage from their other social networks as much as possible. Don't ever let their work performance influence your attitude to them at home, for instance. In fact, pretend you don't know anything about their job. Definitely don't do things like "I know you're so busy at work, so it's alright [to break promises you've made before]". Might be good for boosting the skill of coping with separate social networks.