It doesn’t bother me in the slightest as long as it’s within the paid time, and very often some guys just want to know that they can cum again even if they know they won’t, it’s psychological.
Now I grudge guys that want to come twice in a 15 min booking, they get a firm no if they ask!
What I will say is that if a man books half an hour and takes 20 mins to come the first time, then round 2 won’t even be attempted!