Wrong again. If you IAM bounces arround a lot it means you have major knock problems because of a crappy base fuel and base timing map. The IAM should advance and stay put no matter where you are in the RPM range. The IAM doesn't change throughout RPM range... where did you get an idea like that? As for tuning for fuel advancement, pushing the limit of the IAM vs KC values is where that lies. You can do some tuning to take into affect if someone runs better gas, but that advancement should only be in the IAM of 14-16... maybe 12, but that's pushing it. One VERY KEY factor you need to remember is that the ECU will try repeatedly from time to time to advance the IAM to test and see if you've got better gas available or not. If the ECU constantly tests for this and your knock events are too severe over time you'll kill your isht. This is why you tune for 1-2 points of octane below what you will run and get it to run at about an IAM of 14 consistantly under that tune. Advancement of the IAM will happen if you run better gas and inturn pull up better KC values from the KC maps to go along with it.
Bottom line... if your IAM drops below the onset point (in case of Cobb... 12) then the tune is not right for the car. The map is crap. The IAM should either advance all the way to 16, advance slightly maybe to 14 (and increase to 16 with really good gas) or stay steady at 12 without any negative KC values (while maintaining at least a 4-6 positive KC value).
Negative KC values (even for a moment) and jumpy IAM values = The Suck Map.