If you're signaling the attempt (got the shooter up & down) which is NOT in your PCA, how could you possibly referee your PCA to the best of your abilities?
Even if there is no competitive match-ups in your PCA when the shot goes up, do we really need to extend in the direction of the shooter?
Extending to the rebounding area of the court would be wiser IMHO...

I'm not speaking on fast break situations, just typical half-court settings.