I had a regular who would always book a half hour app. I enjoyed his company so never paid much attention to him overstaying, but as time went on he would deliberately delay and avoid cumming until the very end of the booking, dragging out the appointment more and more.
Over time this really got on my nerves.
The last time I saw him he again kept delaying, it got to the final minute, only this time things didn't go quite as he planned as he must have "gone past the point" or his penis was as pissed of with his constant delaying techniques as I was and he couldn't cum. I'm pretty good at what I do but there was nothing happening and it became clear, to me at least, that it wasn't going to, not in my time anyway.......
I called time on the appointment and sent him away to deal with his frustrated cock himself.
Harsh but fair I think.