As a general rule of thumb, FP usually will make up about 80-90% of the riders. There are exceptions to the rule, and the mix can vary based on demand/attraction/CM working merge, etc. For instance, TSMM is supposed to be 2 tracks for FP, 1 for standby. And as mentioned, when there is a closure, those anytime FP will potentially cause havoc later on. We saw the FP line at EE last trip reach back across the bridge heading to Nemo. The ride had been down a few times during the day, and when it come back up, lots of people ran over to try to get on. Parks that have a smaller amount of desirable rides will stack up even more. Or on days where several headliners go down for a stretch. If SM, Splash, and PoTC go down over the span of the morning, even just for a few minutes (entirely possible, and heck some days even likely) thats alot of people to get absorbed into lines later on.