At XJT if you don't get used in those 4 hours, it's SO LONG.........

If a pilot is assigned airport ready during the evening, he is free to leave 30 minutes after the last flight has left, or after 4 hours. Whichever occurs FIRST.

Can't be assigned airport ready two consecutive days, nor more than 6 times in a bid period. Can't be assigned to report for airport standby later than 1300 in domicile on your last reserve day before days off.