The implication I see (I am not an expert) is that stress was/is used to get our ancestors and other mammals out of short-term problems, i.e. to escape a predat

The implication I see (I am not an expert) is that stress was/is used to get our ancestors and other mammals out of short-term problems, i.e. to escape a predator. It's not useful or healthy as a lifestyle, or else evolution would have favored the "baseline" of modern humans to be closer to what our "stressed" state is. It seems to follow that stress is useful when it's really needed to make you sharper, but one should prioritize getting out of that state as soon as possible.