As a few commented, it depends on the situation - surgeon, driver etc. I, personally, try to push through and get it all done. When I feel that I'm not achieving anything anymore, I stop, and take a rest. It's a better rest then, feeling that I got something done and deserve to rest. It's not the most healthy mindset, and I try to organize my life in a way that prevents getting tired.

In my experience, being tired makes me less efficient as well. A lot of times it works better for me to be rest in time (meaning, when I notice that I'm not achieving/being efficient), and then get back to it refreshed. The thing is that resting is not easy in that case, as my mind is still roaming through the tasks. I got better at it, through meditation techniques.

Now that Lily is with her mom, I did lose a lot of structure. No more schedules, no more deadlines, no more appointments. It's nice, I can rest well, but I notice that it also makes me "lazy" in a sense. As I have more time, I waste more of it.