This question... I have spent far too many hours contemplating it. I have discovered multiple answers depending on how deep you want to go.
The most pragmatic answer: you want to win a marathon, not a sprint. Too much sprinting makes you worse at marathons.
The hard part, of course, is knowing how much is 'too much sprinting.' But in my experience, if the person thinks they need a break, they need a break (or, more extremely, they are not a good fit for the company.)