Very true. I think part of it is that with most regular room perspectives the perspective points are so far off that construction is always cumbersome, or you have to resize things and such. Have you read "perspective for Comic Book Artists" by David Chelsea? It's a comic book about perspective and explains not just the construction rules, but also has tips and shortcuts on how to more succesfully fudge perspective without doing a full construction. I found it a bit hard to follow in places when it got to the more complicated and finer points of perspective, but overall it's very cool, and that it's a comic helps.