Since we are on hacker news, a forum seemingly overrun by silicon valley devs, I didn't expect your comment to focus on that kind of work. But when we look at physically demanding work with a decent amount of brain work, for example some kinds of woodworking, you can still see that effect. People can work longer hours and more days to a certain extent, but then the rate of accidents goes up (and I'd expect it to behave in a non-linear fashion). And if that effect is true in that direction, why should it not work for less than 40 hours?

> I doubt many people can sustain their work output over 16 hours for most jobs. But that's not really what we're talking about here.

Apparently, I'm no good at making myself clear. It's probably the language barrier, I'm decent enough at understanding English, but I lack any sort of conciseness, I believe. This was meant to be an extreme example, to make the point more obvious, but let's use a similar, more normal one.

Let's say instead of moving to a 4 day workweek, we move back to a 6 day workweek. Daniel you believe that you get 20% more output than before? Even with physical jobs that don't involve too much brainwork, I believe that this is not the case, as there are diminishing returns when the time for recreation is cut too short.

That depends on the individual of course, younger people need less than older people in general, and things like children, disabilities, a long commute and a host of other factors can change the equation, too.

> I don't understand the argument that working less doesn't mean you get less work done in general.

The argument is basically that for brain work, if you spend 20% more time per week at work, you might only produce less than 5% more output, since your brain will otherwise produce too many errors, which cost time to correct.

That is seen as an inefficient use of an employee's time. Also, his implies that maybe we could get almost the same output from people who work a 4-day-workweek. Now the question is, where is the sweet spot, as it is unlikely to be the status quo (that's what I clumsily tried to imply with the remark about the 40-hour-workweek not being"god-given")? This can't scale forever, of course, or we'd all be working 1 hour a week and be extremely productive in that hour :D

But maybe the 4-day-workweek is that sweet spot. And since wages haven't kept up with corporate profits for a while, a lot of people - myself included - are eager to find out.