Not to create a conspiracy theory, but MS is the only attraction that I’ve been on that is always 30-40 minutes less of a wait than the time posted.
Do you ride green or orange? Orange will never post lower than green, I believe. They don’t want to have anyone picking orange because it’s posting a shorter wait time and then have the guest force themselves into feeling unwell because they picked the intense side. So even if Orange is a walk-on and Green is a 30-minute wait, Green will post a 30 and Orange will post a 35.