The most with a sexual partner was 6 times throughout the course of an evening. If she hadn't been drinking so much, I probably could have done more. I was 30 at the time. Normally though I go for two orgasms with my partner when I'm having sex.
As far as masturbating, the most I've done in one day was 18. I was keeping count just to see how many I could do. Towards the end I didn't have any cum left, nor was I completely hard. However, I still had the wonderful feelings of having an orgasm. I was in college at the time. A couple of years ago I got up to 10 times in the same day, but that was it. I must be getting old...
Anyway, my two cents.