Joey said:
I often wonder how much something like a single rider line potentially slows down operations, though. Or like, how often does calling "any groups of two?" down the main line and waiting for them to eventually get to the front actually outweigh just sending it.
As you said, it depends on staff and whether or not they're working efficiently. It really has to be implicit in the training and the general expectation. It does work. It works brilliantly, but only when it's a "normal" part of operations and the staff are working a couple of steps ahead and not focusing on a train that's already sitting in the station.
It's almost redundant to say it now, but look at Disney and Universal; they've got it spot on. The ride ops are thinking a train or two ahead and seats get filled without holding stuff up. I've seen them send
empty trains on Space Mountain in Hong Kong because riders have spent too much time faffing when they get off and it's better to just send an empty train then let them start stacking.