I don’t know about all Texas schools, but the school where my wife teaches has every protocol you just named. The problem is the secretary who buzzes people in buzzes EVERYONE in.True, they shouldn't need to do so, but unfortunately they'll have to until the powers that be decide to devote resources to increase school security. Locking all doors, buzzing folks in and adding alarms to all external doors is a good first step, but schools will need to do more.