With the exception of the very first party, I'm not sure this is true.
We were at the third party (8/28) and the rides were almost all walk-ons with the exception of 7 Dwarfs which we chose to do immediately after the rain stopped at 7pm, in case it started again and the ride was closed. Space Mtn was 13 mins from the moment we entered the queue until we got on the ride. Tea Cups we waited 2 rides and then were on. Aside from this our waits for Buzz, Under the Sea, Big Thunder, Pooh, People Mover, Splash were all walk-ons.
Reports from Monday night's party were that wait times were even less than ours.
Yes, the waits for characters can be crazy long (talked to someone who chose to wait 3+ hours for Jack and Sally) but the longer waits are not for rides.