[KenWittlief]

hooking extra muffin fans all to one breaker is ok.

I suggest you take an old motor apart sometime and look at how its constructed. The amature inside the motor does not touch the case at all, and that is what turns into a space-heater when you stall the motor.

The drill motors and FP motors have internal blowers that suck air across the windings. The CIMs are sealed and have no internal airflow.

The point is, blowing air across the outside of the motors is 99% psychological. It will have no effect on the windings inside the motor. If you tend to overheat your motors you need to gear down your geartrains to keep the motor RPM higher.