About a 1/2 dozen thrusts.
But, that being 26 years ago, at the tender age of 16, I kept going, maintained my erection for 2 more orgasms, or between an hour to an hour and a half. I fell off from sheer exhaustion. And when I say fell off...I mean fell off. We were doing it on a picnic table in a park.
Oh, to be 16 again...for just...one...day.