My son to take official visits to their schools after he has committed to Hawaii and he declined both and told them straight out he would not be taking any more visits or changing his mind. He cancelled a trip to Appalachian St. we were supposed to take a couple of days later that had already been booked.
If a kid is really committed he tells those other schools he is really committed and doesn’t give them any reason to keep pursuing him.
I don’t think many kids do that, it seems most are pretty wishy washy and open to attention and of course want to take the trips.