Scientifically, your productivity declines sharply after 45 hours and, after 60, you're just making mistakes. I'm pretty certain that Elon is NOT working 120-hour weeks - people who claim excessive hours normally count the time they spend thinking about work as working, and we all think about work when we are not at work. Besides, Elon has lied about pretty much everything else. My job tried to force me back to the office, so I quit and joined a 100% remote tech company. The old company is shrinking but the new one is growing, so I guess it's working for them.