One hour, never longer. I've stayed longer but that's not in my time, there's been a few I've got on with over the years and had a laugh & a brew etc on their time after the podging is done. I don't expect sex outside my paid time though.
As a rule though, I'm ready to be making tracks after an hour anyway.
An hour is already eye wateringly expensive, I see no need to stay longer, for me.