Too funny, several times we boarded a bus at Music with guests on it from Sports but didn't stop at Movies. One time in particular was going to Epcot, a man and his daughter from Sports were on already, I chatted with him and found out he used to live in the same part of metro Denver we do. So that one stuck out in my mind.
And a few times midday coming back from MK, we did share a bus. Not a biggie since the bus, even with the three resorts sharing, was mostly deserted.
My main point in all of this is to say the All Star busses were always great for us during our most recent 9 night stay. We didn't always share, not even close and the waits were generally minimal. DTD/Typhoon Lagoon being the exception. But that happened at the next resort (OKW) too.