The other thing I've observed, is people are saying "I was running XXX with a Bama tune, but after 40 runs I switched to XXX and my times are better." You don't think 40 runs down the same track have helped hone your driving skills a bit? How much of the increase in performance is from the tune? How much is from the skill they've picked up?
Some people like me ran them back to back on the same night. :-p