As much as I love the fast pass, I don't think that they should let you use them if they have expired. I wouldn't be in a hurry to get back for the ride and it would make the fast pass line later in the day longer. Does that even sound right?:hammer:
This is so "logical" that most think that it "must be true."
"Late" FP returns are not the overwhelming reason for "slow" FP lines.
Its just not mathmatically the case.
The chance that "everybody" (or even MOST) who got FP earlier in the day but didn't use them, all showing up at the approximate "same time" is actually very small.
What slows down the FP line is RIDE POPULARITY and the overwhelming number of guests in the STANDBY LINES.
That's the part of the equation that eveyone forgets.
The late afternoon/early evening is when many of the lines are very long... about the time the most number of standby guests are clogging the queues.
The CM's don't just load the FP line... they also load a LOT of guests from Standby.
If they DIDN'T load great numbers of Standby guests, those lines would virtually swell to several hours wait-time... and they can't let that happen (especially after the FP have "run out" so early in the day at the few most-popular attractions.)
So by filling the attractions with larger numbers of Standby guests, the FP lines natually slow by an analogous amount.
Are the FP lines "slowed" by those using "expired" FP's... well, sure, but not enough that it really matters more than a few minutes one way or the other.
Here are some FP numbers to play with.
Let's assume a given round number of FP Distributed for Big Thunder Mountain (100 FP's given out).
35 will be used at the beginning (within the first 5 minutes) of the Return Time "window."
40 will be used at some later time, but still within in the specified Return Time "window."
15 will be used outside (later than) the specified Return Time "window."
10 will be pocketed and never used (guests got busy elsewhere, left the park, etc.)
Those not ever using FP and those using FP outside the window (late) can virtually cancel-out each other in the FP waiting-line.
'Jockey' any of those numbers a bit, if you like, but they should be very close.
The FP system works very well, and with proper "policing" by CM's (if the FP lines do get "too long" during a busy run -like Soarin' or EE- they can refuse a "late" FP at that time) the lines move along pretty well under such heavy conditions.