No.
You are allowed to leave as soon as your task you are presently in is completed, hence the name. EXAMPLE: If you are in the middle of a flight that leaves at 22:30; but the time is now 22:20 and you get off at 22:30, you are required to stay and complete the flight. Once pushed off, then you can leave and get paid the 1 hr after 22:31 even if it takes a minute over your time. The supervisor cannot make you stay for another task. PERIOD. (unless you are dumb enough to volunteer) He/She has to sign your exception card and find someone else to do the next incoming that comes to the gate you are working, or wherever UROC sent you. This is now strictly enforced. Management cannot make anyone stay, unless Mandatory is called (well ahead of time, and lists are posted). The good thing about that is no more exception cards are needed on Mandatory - if you are selected, the computer has already put that in the payroll system.
Since I work late, someone has to close out since RON's come in around my exit time. The supervisor signs my exception card in advance, and I get paid, even if it is one minute over. And if the supervisor ask me to start earlier - before my shift time starts, (ie: someone is missing on the previous shift and a plane has to be brought in) I get paid TASKCOM (1 hour) on the front end of the day as well. So it is possible you can get paid for 10 hours within a 8 hour workday. Once I leave, there is a NightHawk crew to finish off the night and prep the HeadStarts the next morning.