I took a model private once who climaxed way faster than I could, so I kept asking her so stick around a little longer. After three times she cut me off, and went to run errands or something.
I had another model leave the cam sitting as she left the room with another model to do drunken stuff with, she never came back so that was frustrating for more than just the lack of talking.
Sometimes models are just busy too, or I need to get ready for work, so I only have so long to play around.