They way it worked is you could only hold one at a time. You'd go to the ride (or pull up the app) and make your reservation, and they would give you a return time, usually an hour or so later, but sometimes many hours later. You'd show up at that time and skip some of the line. Then you could get another fastpass.

So you had to optimize your pass getting since you could only hold one at a time. You'd have to know which ones would fill up and get those first, and then get the less popular ones later in the day.