[Timberwolf]

Something I've noticed about the culture of "work through midnight if that's what it takes" is how much work gets thrown away. I worked at a few places with this culture (startup and established), and it seemed entirely normal for something to be the most urgent thing ever at 9pm and then, "actually, we've decided to approach it differently" the next morning.

I think this is because the impact of an error of commission is low. The worst that happens is people work a bit later, and since they're always working later... well, it's fine to build things that don't need building and have meetings about things that aren't happening. Nobody worries about wasting time because it's just pushing work into a buffer that is treated as infinite. But with limited incentive to select high-value work, it's easy to fall into a trap of working 12+ hour days entirely on low-value stuff.

"Go home on time" cultures are forced to prioritise to be effective. If you know you're going to shut down the laptop with tasks unfinished, you have to make a choice on which tasks you're willing to accept not getting done today. In this situation there is a significant impact of an error of commission, because it means something more important not getting done. IME this results in higher-value work overall, because the organisational instinct tends toward scrutinising everything to see if it's worth doing, not just the things which will take you past 5pm.

I've not been fortunate enough to work somewhere with a 4 day week, only places with generous working hours, but my feeling is it would be a further improvement on this. (Especially since with more free time, people are not going to assign such a high importance to doing their finances, keeping track of Reddit, daydreaming about DIY or any of the other thousands of things people in long-hours cultures do on company time).