Although that would be ideal to get ride of those pesky complaints about "I felt rushed through the attraction", to a budget stand point, that means that ride would have to employ a lot more people than it has now. If you're saying that is a TM per room, to control the flow of guests, that's like what, 6 new positions? Also, with the three lines starting out front, that would add more confusion, so you would need 2 greeters plus a test seat person. Let's break it down, shall we? Let's look at all the positions on the ride now, and add in your new ones. This is if the ride is running at full capacity.
2 Courtyard Greeters
1 Test Seat
2 Dungeon Greeters
2 Queue Control
1 Grouper
1 Child Swap
1 Belt Pulse
1 Load 1
1 Load 2
1 Dispatch
1 Unload
2 Controls Attendants
1 ADA Runner
1 Secondary Platform
1 Castle Queue Patrol
1 Outside Queue Patrol
We're up to 20. These are just positions, no breakers, no Leads. Add in yours:
1 Dungeon Queue Flow
1 Oxford Corridor Queue Flow
1 Portrait Gallery/Dumbledore Queue Flow
1 DAFA QF
1 Common Room/Fat Lady QF
That's 25 positions. Add in breakers, and leads, and that's a lot of staff for 1 attraction. I'm not saying it's a bad idea, I just think that it wouldn't be done. Also, I think the crowd control would be a nightmare. Just let them be in a line, and get on the ride. General public guests wouldn't be able to figure out this whole "wait and watch the show" thing anyway.