How many hours are we talking regarding this masturbation period? I'm wondering what your recovery rate is like. My first ejaculation is always significantly stronger than subsequent ones, but usually I can still manage a minor spurt out of the second one. Third and beyond, though, it just pours down the side, no eruption. In fact, a few weekends ago I had masturbated a few times in a night, and even the following morning when I masturbated in my bed in what should have had a respectable climax, it just trickled out in a weak spirally pattern like some kind of gay phallic Sharper Image fountain.
Repeated orgasms have increasingly diminished euphoria as well, I find.