Overteaching is something that is a problem. One day when I was in a relaxed mood, I began saying less and noticing more. Errors that I saw but didn't mention were correcting themselves without the student ever knowing he had made them. Sometimes verbal instruction to a conscientious student sometimes decreases the probability of the desired correction occurring. All teaching pros are aware of this phenomena.
Images are better than words.
Showing is better than telling. Too much instruction is worse than none. The conscious trying often produces negative results. Reflect on the state on mind of a player who is said to be hot or in the zone. The common factor in each of these descriptions is what might be called mindlessness.