It's also the easiest to implement, imo. But there is a tradeoff: fewer waking hours during your best years cognitively for more years when you're older...

Poor sleep is a widespread problem and very few of those people are cognitively doing it intentionally as some sort of "tradeoff". The number of people "grinding on a startup" is tiny compared to the population of people who suffer from this problem. Instead it's caused by things like general anxiety, too much screen time before bed, or not having consistent sleep schedules. And other health related reasons that compound the problem.

Waking hours is both a quantity game and a quality game. I don't remember too much from the parts of my life where I was very sleep deprived