I have never had ball pain from cumming so much. Yes, after the 4th or 5th time the amount is like 1/2 the usual (if I had cum the previous day), but I always have something and my balls are always ready to go.
Now, if I don't cum for like 3-4 or more days and finally do.... it feels like it's never going to stop and I get a little bit of WTF pain.