Ok after reading some other threads another question has popped up for me. What if he hasn't managed to cum in his allotted time?
Sorry for the constant questions. Hope I am not being a nuisance.

The ones who don't cum with me hold back delaying or have some mental blocker. It is a psychological thing. For example when they get semi then talk about going soft touching it it goes soft not coming back up it is no coincidence. One gets what they ask for. I say to clients to think of my boobs when this happened. One time he did and he got hard. I knew his chances was more likely.  See... It is mental=brain determining the out come. It is like when clients are down on themselves you see it happen. Call me skeptical but I call myself a being realistic.