We noticed on our last trip that the timings outside TSM aren't always accurate.
We do the "arrive early, ride TSM, then get FP" or "arrive early, get FP, then ride", that way we always get to go at least twice. And with arrive early, I mean, front of the rope drop early!
But we've noticed that when we come back to ride with the FP (usually between 10 and 11am), that the sign will say 50 minutes wait. However when we go in, the line inside, isn't anywhere near that, more like 20 to 30 minutes. At that point we've switched lines, wasn't gonna waste my FP if there was a short line. One day on our last trip (November) we managed to ride TSM 4 times by 1pm, twice with a FP, twice just doing the line and never waited more 25 minutes even though outside it said 50 minutes.