It depends... If I only have ten minutes to 'crank one out' maybe only 3 spurts will shoot out. But if I go at it for a long while by myself, or if my girlfriend and me are really getting into it, I can shoot out 3 times that amount like nothing. Now, when I was in my youth, I used to sort of marvel at the larger loads, and the fact that they were often bigger than anything I seen in any of the pornos I watched... But now when having casual sex, it becomes kind of aggravating (Don't get me wrong, bigger loads seem to produce bigger orgasms, which is always nice) since it becomes more mess to clean up afterwards and since we're not trying to have a kid or anything what use is a big load?
As for a story, something happened a few months back that this topic brings to mind: We were going at it like normal, and usually we try (and sometimes fail) to cum at about the same time. Anyways, she started to climax and for some reason (probably from a foreign substance) I just couldn't climax no matter how bad I wanted to. She decided afterwards that she was actually willing to go down on me to see if she could finish me off that way, and since she very rarely even tries this (the girth is too much for her she says), I managed to cum in very little time at all. However, after going at it so long before, and since she is really inexperienced at it, by the third spurt or so she took her mouth off of it... and I started shooting all over her hair and face, on the floor, and inside of her purse which was next to the bed. After much apologizing, she was still pretty pissed, and I ended up buying her a new purse.