When you apply for AP, you could select an option for multiple travel so that way you don't have to apply AP for each time when you need to travel.The duration of your travel should be less than a month to be in the safe side and it should not cross more than 2 months at the max. The allowed travel start date and end date will be given in the AP document once its approved.
I have few scenarios which I would like to lay down for further discussion.
a. A person is in H1b and has visa stamped and applied for TPS and TPS has been approved. Does he/she requires AP to travel?
b. A person is in F1 and has a visa for 5 years? Does he/she requires AP?
c. A person is in H4/F2/B1/B2 visa? Does he/she requires AP for travel?