completly disagree. Just because you have them doesn't mean that you should use them all the time.
I hate those guys (inclusive the mechanics) who turn it on all the time just to cover their a$$. If you think a little and plan ahead, you hardly ever need them, except for very short turnarounds or heavy braking.
Ideal braking temperature is around 100-200 degrees, so keep it there, don't cool it too low.
Dani