I believe on pick-up they go to all star sports first. If it is close for you, you can walk over to sports to get the bus. If sports fills the bus, you will have to wait for another.
We stayed at Movies in 2002, and were shocked at how fast the bus service was. I don't think we ever waited more than 5 minutes for a bus in or out of a park. We wondered if the budgets got more buses, since the service was fantastic. For your sake, I hope it still is!!