Do humans actually need breaks from working, physiologically? How much of this is a cultural construct? And if it is, can those assumptions be changed? Could a person be trained to enjoyably have 100-hour workweeks? (assume, if the book Deep Work is correct that you have max 4 hours of highly productive work on a domain, that my putative powerhuman is working on 2-4 different skill domains that synergize)
I think you think I'm making assumptions I'm not. I agree with all these points – this is why the world looks the way it does. I'm saying, if there weren't the sorts of limits that you're describing, we'd observe people working more, more often.