That makes total sense. Its certain that some photographers will become very busy, but one of the most important spaces is the one nearby which is fairly easy to keep track of.
There is no professionalism in allowing the best possible photos to be slowly replaced by table scraps.
I am only guessing your reference to important spaces nearby, you are a more close positioning shooter so that is what you mean by keeping track of them. But imagine my son down on the floor in the back of the church with his 70-200. the center aisle is decorated with candles or flowers going up on either side to the altar from the rear, you have this beautiful church setting as the backdrop, the officiant just announces man and wife, they turn to face everyone and make those great first gestures, kiss with a dip or whatever might happen, and Aunt Betty jumps into the aisle to get the shot with her cell phone. This is all we are trying to prevent by making them aware of what could happen. Just managing early on by covering all the bases, so we can give the bride and groom what they paid for. Our creativity and fantastic photos.