For a lot of knowledge work I think it's closer to a bell curve, in that if you work too few hours you'll be swamped by overhead, but if you work too many hours

For a lot of knowledge work I think it's closer to a bell curve, in that if you work too few hours you'll be swamped by overhead, but if you work too many hours, your per-hour productivity drops due to lack of focus caused by insufficient rest or dropping motivation. I thought it was common knowledge that overworked developers create more bugs, so I wonder how a trader is able to work 65 hours a week without performance suffering in the long run. Or could you rotate traders in a one week on / one week off cycle?