My record when I was 18 was seven times in one day. Hickboy's post brought back a few memories of being red, raw and throbbing and still having to knock out just one more (in case it was the last one ever). I used to use that excuse all the time. Keep things moist and lubricated and you won't do yourself any permanent harm.
Seriously though, everyone's different, and you shouldn't let anyone's ideas dictate how often you wank. Once a week might be right for some, ten times a day for others. Find out for yourself how many times is right for you and have fun doing it. Just remember to change hands now and again or you'll end up lopsided!