While this is true in theory and probably more so with glow, I have found my outrunners need air direct through the windings. Not just over the can. Otherwise the windings will get too hot. The outside of the can may feel adequate after landing but the windings will be very hot. After the plane has been on the ground for a few minutes feel your can again, it will be hot if your windings aren't getting adequate cooling. It's tough to get air through the windings though on my motor. I run a bigger gap than normal behind the spinner plus other stuff.
But, I will say that with a depron former directing air out of the exit hole I have found it also helps cooling.