The claim to be answered is not 'people can't be productive working more than 40 hours a week'. It's that people would be more productive if they worked less. We don't have to rely on vague anecdotes and 'what about people who are really really sure and feel it very deeply that their personal sacrifice wasn't counter-productive? Shouldn't we just believe them so they can feel their exertion wasn't wasted?' We've got research.

But its quite important to make a distinction between manufacturing work, repetitive physical labor, and mental work. Different organs are involved and they function differently. As nice as some might imagine it would be to only employ machines, in reality we still have to put bathrooms in the workplace, give people a lunch break, and admit that they're sacks of meat. They've got limits, and ignoring them will never be productive.

You might be right that some people can be productive more than 40 hours per week because I am one of them.

However my point was that when negotiating salary you can't really say "I can be productive 70 hours per week" and therefor ask for 40% higher salary. It doesn't work that way and what you negotiate is based on your skills mostly in comparison to other people who are assumed to put in cca 40 hours per week.

So even if you can be productive for 70 hours per week, I wouldn't do it and instead invest that time in your family and yourself, making your life outside of work richer and more fulfilling. Otherwise you will just be working for free the extra 40% of the time and never be compensated for it by most companies.

Finally, you only have one life so spending most of your life in the office or commuting in and out of office is quite a waste of your time. You should use your free time to enjoy your life imho and experience more things.

>You might be right that some people can be productive more than 40 hours per week because I am one of them.

Is that constant heads down, in the zone coding, or does that include some coding, some management, some marketing, etc? Also, how long can you do that for? 5 years straight?

I typically work in bursts. If I don't have an outlet in between bursts (surfing, 30 minute tv show, walk, etc), the longer it takes to get back into a burst. Being in an office doesn't offer much as far as outlets go.

It's the same for me, I work in bursts. Sometimes I will have 30m-1h of not very productive time (reading blog post on web, going for a walk etc) but then I will have a burst of productivity when I hunker down for couple of hours and do a lot of work.

Obviously it isn't constant 8 hours of heads down, in the zone coding, there are things in between and also meetings and planning often takes time. I used to work longer before but as you say, that is not sustainable for a long run, you can do it for couple of years before you burn out.

I also used to do quite a lot of extra work in the evenings and weekends when I had sudden inspiration / urge to refactor or improve some piece of code. But I don't do that anymore and instead use that free time for myself and my hobbies :)

If I feel an urge to write some code on Sunday, I will work on one of my open source projects or contribute to some other projects out there if they interest me or I will experiment with new tech to keep my skills up to date.

>Otherwise you will just be working for free the extra 40% of the time and never be compensated for it by most companies.

And making your colleagues look bad if you aren't letting EVERYONE know that you are working more hours!

40 hours might be the maximum a worker can be productive on a single issue/project. After a little while you have to do something completely different.