[Kenji]

I cannot get more than 4-5 hours of pure brain work out of my day. Usually, those hours are spent at work, except on weekends. I have no idea how other people do that but if I regularly spend more than 8 hours working per day and then add a few hours of even more programming in the evening, I go insane.

[WalterSear]

I regularly feel that way. But when I stop working on side projects, I feel worthless. I'm sure it's not a healthy place to be. I don't see how side projects could get anywhere without a little irrationality - it's inherently unhealthy to take on what amounts to a second job.

[drmpeg]

Same here. I just couldn't write software for 8 hours a day and then go home and write software. Now that I'm retired, I've been able to contribute to open source (but at a very leisurely pace).