Nevermind that; This is the wrong WAD altogether. Sorry. =/
About that one way thing in Mine maze, I still don't think it's a good idea when the one way path is the only path.
I think to be a little bit more fair, it would be best to make those closers into moving crushers instead. Maybe even review how the stage worked in demo 2.
For example, the very first path close, and the only one really on Demo 2's development version of Mine Maze, there is a second path that opens to allow other players to get through. This would indicate that the original level designer was already thinking about this problem.
I'm sure you also noticed that the first crusher also rose up from the ground too?
Also what's the player suppose to do if they trigger the one time crusher that doesn't reset and wind up on the wrong side of it? there is dangerous, and then there is impossible.
(also Sonic 2's Mystic cave had the repeating crushers too)