And what if that upper bound is an extremely loose upper bound? Say a deterministic quick sort has an upper bound that's quadratic in input size even though typ

And what if that upper bound is an extremely loose upper bound? Say a deterministic quick sort has an upper bound that's quadratic in input size even though typically it's linearithmic? Do you refuse the computation of quick sort then? Or more dramatically consider the Hindley–Milner algorithm which has an upper bound of exponential time even though in practice it runs in linear time?