I don't think anyone disputes that from a given physical point in the standby line, wait time has increased by a factor of 5 (for example as others have stated for BTMRR, the standby wait time from when you enter the building should have increased by a factor of 5).
I've recently come up with the following hypothesis that has some explanatory power to understand some of the behavioral economics involved in standby wait times even if it doesn't strictly represent reality.
- Let's say that there is a non-trivial subset of park guests who are driven by emotion and who show neither great forethought nor great planning skills. I'd like to call them the Amygdalas.
- Amygdalas have a set of attractions that they would like to ride on, and for each they have a "wait time" price that they are willing to pay. This wait time price (WTP) is different for each Amygdala, and it reduces a little each time the Amygdala rides the ride. So Amygdala 1 may have a WTP for FoP of 3 hours, but after riding once, their WTP for FoP may reduce to 2 hours.
- My conjecture: The standby wait time for an attraction like BTMRR is determined by the WTP of the set of Amygdalas in the park at the current time. And though this population of Amygdalas changes from day to day, it remains stable enough to make generalizations like, "BTMRR standby wait times are almost never less than 1 hour, except during a parade" and "BTMRR standby wait times are almost never greater than 2 hours".
Under this model, the posted standby wait times wouldn't change
that much between different FastPass schemes because standby wait times wouldn't be primarily determined by the number of guests that are flowing through standby vs fastpass queues, but rather by the going "wait time price" that the Amygdalas currently in the park will put up with.
I'd love to go further, but I'll wait to see if anyone finds this idea at all interesting and worth discussing.
tl;dr - the standby wait time for attractions at a given time for most popular attractions may be driven by the maximum wait time people currently in the park will put up with, not by how many FastPasses are given out