It's absolutely maddening to see so many people work a job they don't want to work, so that they can pay for stuff they don't really need. Time is by far the most valuable "thing/piece of stuff". How much are you selling an hour of your life for (the whole aspect of the hour... time away from your family, time away from the things you enjoy doing)? Is it worth it?
Working part time for a couple of years now makes me realize how non-conventional it is. I'm the only weirdo I know in my circle of developers that's working part time. It seems to me that money is overvalued and that very often people like to sacrifice time in order to accumulate more money. But is more money equal to better life quality all the time?
I don't think so.
I'm pretty happy working half the time for half the money I could be making, so you could say that I'm sacrificing money in order to get something more valuable for me - more free time. With that free time I have an asset with which I can choose to do whatever I like. Currently I'm choosing to work on a side project and open source since I think it's a better investment in a career than working full time.
After you have a pretty crazy amount of money for a while, you start to slowly realize it doesn’t mean a whole lot. Time and doing (or working on) things you care about is a lot more important, and variety is healthy, if you’re interested in other forms of art, sports, whatever. Doing one thing, all day, every day, is not.
I think learning aside from working for clients is essential for career growth. I think sabbaticals, when they are paid are a great way to learn things. Unpaid are a little tricky for me since not having an active income puts pressure on me, since I have living expenses and no income.
I used to work full time for some time and then went on vacation for a couple of months. That didn't work out because of the mentioned pressure. I ended up with $0 in my pockets, since I couldn't find the incentive to find a new job and kept delaying it in order to do more learning.
That's why I switched to working part time. Working this way makes me in check with reality. I don't get lost in all the side projects and I don't end up broke this way. There are downsides though.
The biggest downside is definitely having to prove yourself when other team members are working full time. There's always a risk of coming off as not being engaged enough. There's always a pressure of working more and it's coming from all the directions. Having the discipline to switch off after ~4 hours of work every day takes some courage.
Another downside is that part time jobs are difficult to find. No one is eager to offer you a part time job in a workaholic culture where working +40hrs work weeks is often glorified. That's why I don't consider most startups as my potential clients. Combine that with the fact that I suck at technical interviews and my mode for job search is super hard.
All in all I think having free time for yourself and for learning more on the side is beneficial for career growth. I think nothing contributed to my career growth more directly than working part time for clients. Money isn't everything, sometimes time is your more valuable asset.
Having the time-money balance is essential. Knowing how much free time and how little money you need is crucial for having a good quality life.
I spend most of my time enjoying other things now, I write code 2–3 hours a day unless I’m really into something. Time is your real currency! Money is nice and all but don’t waste your time. If you really enjoy the project(s) you’re working on then go for it but don’t neglect other areas of your life (or people).