Too much optimization reminds me of what happens when removing all slack from supply chains: when it fails it takes down the whole system. I'd leave some ineffi

Too much optimization reminds me of what happens when removing all slack from supply chains: when it fails it takes down the whole system. I'd leave some inefficiencies here and there, we're human after all. Of course, I'm not talking about gross inefficiencies. But are there any? By what measure?