To be a good teacher you have to be good at making decisions. Teachers make decisions within and outside of the classroom.
Some decisions are made on the spur of the moment. "Should I separate the two fighting girls?"
Some of the decisions are a little more subtle. "I've never really taken to J.... so I think I will let it continue a little longer as K.... is really in command."
So some teachers will just go on and on about the pet topic and not simply allow the child to set his or her own pace. (At bit like some parents?)
There are sometimes strong feelings on both sides about a premise that can not be changed. (Should the extra work be done at all!)
A child will very often feel that he or she is right - no matter what. An Eleven Plus child may be able to ague without whine. When you as parent hear the discussion and there is remarkably little emotion, it may be time to make a decision.
Withdrawing from a a position where there are no winners and losers is a hard task for many parents. Teacher have to face the consequences of decisions day after day, lesson after lesson.