The way I see it there are only a few reasons that I would ever do a side project.
1. To make more money now by freelancing.
2. To make more money in the future by learning new skills or heck at the point, just to keep up with the technology to stay employable.
3. A great idea that I think I can make money on.
4. For fun
----
Taking those reasons into account:
1. We make enough now to be comfortable and I'm not willing to prioritize making more money over exercising or spending time with my family and friends.
2. I try to make sure I have a job that lets me keep learning. I'll spend extra time at work trying to figure out a new to me technology to incorporate in my job. That's the quickest way to learn how something works in a real world environment.
3. I really don't have any great money making ideas.
4. I find coding and problem solving "fun" That's why I enjoy my job. If I'm not enjoying my job, it's time to get a new one.
But I do spend maybe 5-6 hours a week studying and watching tech videos in my downtime or when I'm working out in my home gym.
Trying to start a small business in your free time? Probably a lot of hours. I wouldn't be surprised to see people spending 20+ on the weekend for this.
Trying to beef up your resume for an imminent job search? Less than the start your own business guys, but a good amount. Maybe 10 hours on the weekend.
Do you just really, really like programming? No limit here then. As much time as you can while still eating, sleeping, and keeping your spouse happy.
Is it just like any other hobby to you? Probably <10 hours in most cases. It's not like you have any reason to finish in a timely manner and you probably have other hobbies to get to.
Have a 9-5 tech job that you plan on staying in for a while? Most people in this situation are probably at 0 hours. For most people it's just a job. No need to bring it home. Also, once you have kids and other responsibilities side projects will be one of the first things to go.
Anyways, my point here is that unless you're trying to monetize it somehow, either by starting a business or getting a future job, just do it however much you feel like. 0 hours, 10 hours, 20 hours, it doesn't really matter. It's supposed to be fun. There's nothing wrong with sitting in front of the TV all weekend, or camping all weekend without any technology, or doing anything else you want on the weekend.
A lot of people on this website have drunk the productivity kool-aid, some for good reasons, but it tends to be a little extreme in my opinion. There are better things in life to be than productive.
What I find is that if I am irritated with my day job, I do better side work. If I am irritated with my side job, my day job work quality is better. There's like this pendulum of me wanting to escape and I found harmony in having 2 things I generally like that also piss me off enough to oscillate back and forth between them. Occasionally I get delusions that my side project is on the verge of a breakout, and reality might smack me around into appreciating my day job more.
You could say I'm in a stable state of general productivity throughput, but the project that benefits varies.
2.5h in total, 1 of that on the weekends. At most. (because I also love my girlfriend, reading, culture, music and need to cook a bit, tidy a bit, relax a bit etc...)
I sleep as less as possible on Fri & Sat, get about 6 hrs. 2 hrs additional on Fri, 6 hrs on Sat & Sun. Then get plenty of sleep on Sunday. I do house work, yard stuff, the usual run arounds and I've an infant. Where there is a will, there's a way.
On a bad one maybe 6 hrs.
I move countries a lot, and so my group of friends changes with every move. So something I've realized is that if I have a group of friends who are into getting shit done, such as active enterpreneurs, then I tend to put a lot more time into my free-time projects as well. Conversely, when I have friends who like to spend time watching movies and drinking beer (nothing wrong with that, in moderation), then I tend to get a lot less done.
So the answer really depends on the circumstances.
I am trying to learn as much as I can right now, and hoping to one day start my own company or build my own app.
Depending on what I'm doing and how much I want to get done, I'll usually spend a few hours each day between 10pm - 4am.
If it's a new project or a big feature, I'll carve out a large chunk of the weekend to work on it. Maybe start around 10am, work until 5pm... go get food or go to the bar after that. Do it again on Sunday unless I make other plans.
I also do a 3 hour each way commute into the office once or twice a week which I’ll often spend on side projects.
