goeasy,
I understand that the cooling is mostly achieved by heating the air that flows through the brakes, so releasing the brakes - separating the "pads" and "discs" - would make sense both to allow more convecting air to flow between them, and to present a larger hot surface area to it. I'd expect this to hold whether the airflow is natural or by forced air.
I believe that carbon brakes do work better as brakes when the contact surfaces are warm/hot, but that happens fast when they're used. Cooler brakes should give you more total braking power if you have to reject, in addition to being able to stow brakes that won't burn oil if you do take off, as pointed out by Cough.