I might have the record but we shall see, 10 times within 24 hours, with the same girl.
We started at 3pm and our last time for the night was 3am, at that point it was #7. Then we did it 3 more times the next day before 3pm.
Why was I counting? Because we had done the marathon thing often, and then she had previously said she wondered how many times we were doing it, so 1 day I kept track.
The 10 times day coincidentally was the same day I had bought her a piece of jewelry, so maybe that helped, haha.