My plan keeps specifying that SM will take 25 min to ride. Not the wait (which is an estimated 5 min with my FPP), but the ride itself. Now, it’s been a long time since I’ve ridden it, but is that really correct?
25 minutes from the time you walk into the entrance to the time you exit is probably correct. It is a long way to the loading area.
I believe Touring Plans usually estimates the attraction wait time using FPP as a fixed percentage of the standby wait time (around 33%, I think). Depending on where the FPP blend line in this isn’t always accurate.
For Space Mountain, the ride itself is about 4 minutes long, though as @brklinck notes, the journey back to earth at the end of the attraction is almost as long as the ride itself. My wait times using FastPass and FPP have ranged from 5 to 15 minutes, with the average FastPass wait time around 8 minutes. The one time I waited 15 minutes the posted wait was 105 minutes, so I’d look at that as the worst case scenario.
It IS a long walk between the entrance and the boarding (both ways) and ther is a bit of a wait to launch after you board, but 25 does seem a bit long…
Are you doing child swap?
I plan to do child swap, but don’t see that I’ve accounted for it, at least in the app version.
Allotting extra time isn’t a bad thing, I’ll just end up ahead if it’s not required. But I’m kind of sad that I don’t get 25 min on SM… 
If I rode SM for 25 min straight I’d need to be hauled out on a stretcher. Even after one ride I wish I had brought my chiropractor with me… 
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