During this learning mode, the ECU is bascially judging your octane level and trying to figure out how far it can advance ignition timing toward maximum brake torque timing without sufferring too much knock.
The question is does the ECU seek max brake torque by attempting to reach some specific advance setting (ie a fixed target timing), or does it settle at a standard offset from the knock limit it discovers. Do you have any idea which mode it uses to set the max timing?
To clarify, the two possibilities. It could have some ideal timing setting (say 24 degrees BTDC) in its code that it trys to get to if the octane will allow it, or it could always add advance until it determines the current knock limit, and then off sets to a point (say 3 degrees < knock limit timing).