[Retric]

A programmer can usually average ~4 hours of focused highly productive work where they are not on Hacker News etc per day. Fewer people can do that kind of focused effort for ~8 hours a day regularly. I have never met someone that can do that kind of highly focused effort for ~12 hour days.

That does not mean highly focused effort is the only valid type of work. But, it is very valuable for most programming jobs.

Further, cutting back hours often increases productivity even if you spend the same amount of time in the office.

[kamaal]

Modern day programming is so much more than just opening up your IDE and churning out code. You have to collaborate, talk, review other people's work etc. There is also a meta aspect to it to improve you productivity at work by looking at your own work from a level above.

You also have to keep learning new bleeding edge stuff to not be out of business in a few years.

Plus doing a lot of side projects and extra work, always opens up avenues for new opportunities and helps you to meet with other smart people who often have something new for you.

All of this is work. And there is no way you can be good at this if you only work for 4 hrs a day.

[Retric]

Effective leaning also takes focus.

Pick up a programming book in a new language and start reading. You will have similar limits around how much you can really learn in a given day.

That's not to say you can't be productive for longer periods but the sustained intensity decreases.

[alexasmyths]

I fully hear you about the 'focus' ... but again, a lot of tech work is reading, trying things, meetings, etc. etc.

If we 'only wrote code' I might agree that 1/2 days would be max.

FYI - for the the same reason professional orchestras don't 'rehearse all day'.