or
The guide certainly has some variance built in to allow for variation in systems, no doubt, but it isn't infinite. By ignoring the guide for main distance from the MLP, you could conceivably be sitting 25 feet or more from the mains and have the front heights only 4 feet in front of you. You could even assume the mains to be 100 feet from the MLP, and the ceiling height positions still wouldn't change because the MLP to mains distance never comes into play. I'd have to look at my current system to verify the range, but the distances and the difference in distances are not infinite. If I remember correctly it takes the speaker furthest away from the MLP and gives it a delay of zero. All others get a delay time that corresponds with their distance from the MLP. But it isn't unlimited. Neither are the relative levels. I think the adjustment on mine is 10dB from the lowest to the loudest.I personally think you are putting too much importance on the distance between mains and the Front Top speakers. I don’t believe these Home Theater Speaker Guides from Dolby are intended to “implicitly” set up a distance from the mains. These guidelines have a good bit of variance between them as well, 22 to 30 degrees on the mains and also with the diagrams that @ar surround posted above. I believe they are more concerned with the relationship of the Top speakers to the listeners position. The AVR will correct the timing/distances during setup.
Just IMHO!