The thing that happens with MSEP is that just regardless of it's the first or second performance of the evening, the floats are just slowly falling apart and are very temper-mental these days. If they can I'm sure they try to send out the whole parade but things unfortunately happen. However, I think with the second parade sometimes they'll let CM's do an ER(early release) from their shifts, sometimes causing some performers to be missing, but I really have no idea if it's an actual thing or not.