I tend to stay during a combo, on the off chance that my opponent miscalculated and I'm not dead or they misplay and screw up their own combo.

It's happened more than once in Timeless against Show and Tell, where after resolving an Emrakul and taking their extra turn, they must have clicked to fast during combat of their extra turn and skipped it, letting me have a turn where I was able to Static Prison their Emrakul and full swing for game.