Realistically, it is our experience that it takes about 5-10 minutes to accomplish this. This time includes verifying the identity of the remote person, code exchange, and setting a new password. Any examples of 30+ minutes is either a really computer illiterate user or a help desk person who is clueless on how it is supposed to work.
I have some help desk people that can't seem to remember the to have the user click "Cancel" before Options (5x).
I have also had to explain simple computer concepts to end users, like right-click or where the space bar is (seriously). Some of them are baffled by the Shift key, and prefer to turn the Caps Lock on and off.