In my mind the only reason to work crazy hours is when you find product market fit: the ball is rolling down the hill and you're chasing it. That is supposed to be what it feels like. Customers are breaking down the door because they want your product and you're fighting to keep up with demand. And yes the "best" teams work crazy hours because they already have product market fit.

I've worked at a startup that very clearly had product market fit and one that very clearly didn't. In the former example the early employees worked a ton to scale the product and keep up with demand. In the latter example, the founders felt they needed to work nonstop in the mindset that hard work for the sake of hard work would produce product market fit. I think it resulted in a lot of thrashing. They kept focusing on minutiae in the product when probably taking a step back, letting things simmer, and evaluating from a higher level would have been really beneficial.

I think successful product development requires a lot of creativity, and you don't get creativity by sitting in a seat for 16 hours a day because that's what your investors tell you their best teams do...