On ride capacities, it seems like Universal's very many attraction single rider lines basically get every seat filled on those attractions, which greatly enhances capacity. And the loaders are pretty good at keeping those single rider lines moving at a fast clip....Now, at WDW , there's only a few single rider line attractions, so there's lots of empty seats on the 'non single rider attractions'. Also, just my experience, but the times we've used single rider on Test Track and Aerosmith, the loaders were very lazy about using the single riders. Seems like we were in line forever and they weren't filling all the empty seats with single riders, just some every now and then when they felt like doing it.