The 7-8 number is across demographics, be it your family of four with small children or four teenagers. Crowding is good because it decreases your hourly capacity needs thus reducing your build out and operating costs. And since Disney has implemented a ride reservation system, those longer spans of time between money is supposed to be spent buying stuff. People don't like crowding in the moment, but Disney found that at the end of the day it would be forgiven if they got their 7-8 experiences. So many attractions are suddenly being built because 20 years of schemes to avoid having to actually build attractions are finally buckling and the costs is just way too high to keep up, much less get near an industry standard attractions per hour.