Re-posting this breakdown...
25-30 seconds as a dispatch interval seems to still be the bottleneck, but I don't know if there are other hold points between the track switches. The switch itself shouldn't take that long, but if another boat can't be in the flume between the two track switches then that section would be the bottleneck. Here is the timing of the various components on Blog Mickey's video:
- 2:39 - Doors open to Let It Go scene
- 2:51 - Vehicle stops at Elsa
- 2:59 - Vehicle starts backwards drop/section
- 3:25 - Icy blast transitions out of the Let It Go scene
- 3:51 - Vehicle stops at Marshmallow track switch
- 3:57 - Vehicle travels forward down hill
- 4:09 - Bottom of hill
If I had to guess I'd say that the speakers approaching Elsa and prior to the backwards drop kick off right as the boat starts going backwards and you only hear speakers playing the song from speakers near you. That would mean that the loop you hear through the speakers in the Elsa scene is only about 20 seconds.