4 times in 15 minutes is impressive from a “refractory time” point of view…not quite as impressive in terms of duration, though. 
Personal best: 7 times in 16 hours, 2 years ago.
I’m 47.
I think about that day a lot…
Well, I’m 22… after I had my last shot of testosterone I managed 5 times in an hour on an average of 3 times a day.
Sore is not the word.
Unfortunately, it was worse to leave it than to do it.
Damn, that’s a strong urge.