Actually, that very thing happened to me in one of the War holds--I missed a room (possibly intentionally, planning to return to it later) and only when I reached the end did I find I went through a one-way room.
There have also been holds where you had to go through certain areas twice in order to get to certain secret points. The one that comes to mind is
Click here to view the secret text
×Labyrinthitis, in which it's easy to progress beyond a rather early point and get most of the way through the hold before discovering you made a mistake on level three and have to do the whole thing over
. Or places where you should have thought ahead to see that if you kill the tar mother/snake/etc. on this pass through the room, you'll never be able to get back through it.
(In other words: you did feed the cheese sandwich to the dog, right?)
In the end: Syntax may be right that this problem
shouldn't exist; and yet it does. (One might also say, "
We shouldn't need transparent tar, because it's only there to deal with rooms where there are trapdoors/walls under tar; better not to have those rooms."
Well...maybe. But in the meantime, I'm not giving up my transparent tar.)