There is that, the drippings and I think they add to the flavor but don't really affect the cooking time. My guess is that most offsets have big variances in the grate temp next to the firebox as compared to the far end at the exhaust stack. I know it was around 50* in my Bar B Chef and I could not even it out. I tried water pans below the cooking grate, one on top of the cooking grate next to the fire box, added a heat deflector to try and push more heat towards the far end before it rose to the meat.
Some offsets I am sure don't vary that much especially for the comp guys, but for the average backyard guy you gotta do alot of smokin to fix that problem. In the UDS I think the temps are not so varied. I also agree that having the meat 24" from the heat source must have something to do with it but not being a scientist don't know what it is but know it works.
Drumhead - UDS x 2 & UDG
Keep on Smokin'
KC native missin' KC
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