When inverted, CruiseControl has the same effect as reducing the throttle to 5% (default).
CC reducing the throttle (when inverted) does NOT reduce the control or stabilization that is available. If the FC sees that it needs (control or stabilization) e.g. to roll left really hard, it has the authority to run the right side motors at 100% and the left side motors at idle if it wants to.
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For ESCs that don't have an accurate external oscillator, heat does change the timing so that it reads the command pulses a little differently. The result is that the idle speed pulse width that you calibrated with the ESCs cool (say 1065) actually allows the motors to completely stop. Adding 10 to 20 to the number you got when calibrating cool ESCs will make sure they still spin the motors when the ESCs are warm.