Since I'm obsessed with managing my time, the very unfortunate he said/she said in this thread caught my attention. I have no idea what happened in this situation and couldn't care less, though I think it's never a good idea to air these things in public. I do think, though, that the endgame can be tricky. On the one hand, obviously, if you pay for 90 minutes then you don't get an extra 10 minutes of "free" time to finish. But there is another hand to this, or maybe two more hands. For one thing, we all know that SPs often will leave before the paid-for time is up, or shower, or start calling their booking agents, etc etc. The agreed-upon time together goes both ways. Second, I do think that both parties have a responsibility to make the night end well; if the time is up, the SP would do well to end it graciously, even if that leaves the client disappointed. (This is a general principle and not a comment on the night discussed here.)
Two quick stories. Once, in Las Vegas at least a decade ago, I booked two hours with an indy; she was incredible (and later became a major player in the Las Vegas scene) and I finished after perhaps 80 minute. She offered to go for round two but I was exhausted and had nothing left. I told her I had a great time with her and was going to fall asleep. She responded by offering to refund the difference (of course I refused) and she insisted that I had another 40 minutes coming to me and that I should call her the next night. I didn't--but I though that was a great move, both classy and fantastic pr.
The second was in Montreal a year or so ago with an indy. I booked three hours; we started in the hotel bar and I drank too much (I really enjoyed her company). As the end of the allotted time approached, she gave me a 5 or 10 minute warning--and try as I might, I couldn't finish, a first for me. We went past the three hour mark, maybe 10 minutes?, and when I realized it wasn't happening I apologized (embarrassed) and gave up, thanking her. My point is that she let me know that our time was almost up but she made sure that the night ended on a friendly note. That to me was the professional thing to do--and she did it well.