I usually dont offer a second cup unless the guy cums in the first twenty minutes of the session.

If he takes 45 min, then I am not offering a second cup since the second one usually takes a bit longer and he is going to go over his hour trying to get that second cup.    But I do not kick the guy out when there's time left on the clock.  I will rub his back, cuddle, etc with him for a few minutes before either of us gets out of bed.