It's a bigger pain in the ass when the male talent can't cum...
I shoot several scenes a day when in LA, and nothing wreaks more havoc on the schedule (besides late people and no-shows), than waiting sometimes 20 to 30 minutes (or longer) for a guy to pop.
You have no choice but to wait, unless you want to do a fake internal pop, or mix up some fake cum and go to work with that (which usually looks fake).
I've had guys pop early in a scene before, and after a quick clean up and rest, we just go back and shoot some more action, and then edit the pop shot to the end in post-production.
One work around is that I now try to have an extra set of strobe lights and shoot pretty girl still photos of the next scene while we're waiting for the guy to jerk it until he is ready to pop.
With all that said, I really respect the hard work it takes to be male talent (pun intended).
ADG