Your second point conveys what I meant far better. I'm by no means saying one should be a shirker, I mean you should manage your managers by understanding that

Your second point conveys what I meant far better. I'm by no means saying one should be a shirker, I mean you should manage your managers by understanding that their role is to get the most work out of you as possible. Leaving yourself a little leeway is just common sense, as you say, if you're working yourself to the bone constantly and giving people the impression that that's just your standard level, eventually something's going to give, likely your mental health.