Earlier quoted context omitted.
A lot of surgeons have 80 hour workweeks. This is especially common is smaller hospitals in rural areas. It's not all surgery, but they're definitely not sitting at their desks and doing nothing. Before regulations, it was not uncommon for some doctors to work over 100 hours because they were in such high demand.
This doesn't exactly address the point. Human beings are only capable of sustained attention for limited periods of time, plus they have biological needs and must navigate a physical world. Now, if you're just talking about time on the clock, then sure- 168 hours is the limit per week. But we're talking about people doing productive, mentally demanding work. 80 hours might not be possible.
It's definitely possible. Just because we don't want to do it (I don't either!) or that it has negative long-term consequences doesn't mean it's not possible.