If the throttle blades are closed too far, the IAC counts will be high. If the engine encounters a stall situation, there may not be enough 'headroom' for the ECM to increase the IAC to prevent the stall. That's why the 10-20 is important. So there's another 120-130 available to prevent a stall. IIRC, 140 is IAC max counts.
As far as "learning", there's no such thing with the IAC. It's a programmed function, not an "adapt table" like integrator / short term fuel where the ECM fills a series of cells with corrections based on real-time O2 sensor readings. IAC isn't learned, it's controlled to specifications burned into the PROM.
