AP's don't always require a reservation for the parks, it really just depends on the day and the crowd levels. I make them when I plan just to be sure to get one. But on our last trip several of the days had been updated to say that we did not need the reservation and wouldn't let us adjust them (so we were able to just show up wherever).
Also, if you are doing virtual queue in the morning they want you to have a reservation, not sure if it still works if its a non reservation day.