How often to units deviate from scripts?

[Debaser8]

My stupid Kinara cast a 100 fatigue wind guide when he was supposed to be holding. He then followed his next order, attack archers, to the letter, which resulted in him becoming mute. How often to commanders deviate from scripts and what can be done to prevent this? He probably shouldn't have had an air gem, but I was hoping he would use it to reduce mistform's cost.