It’s easy to get stuck in a pattern. You find some solutions that work pretty well and you stick with them. The trouble is that when you’re dealing with the same people over and over, your solutions get stale because they adapt.
This is true of sparring and it is true of teaching. Your sparring partners adapt… so do the students. They figure out your timing. They figure out your favorite techniques and they no longer need to pay attention.
This is no reason to discard your old techniques. It is merely incentive to keep building on what you know. Today in kids class we took a couple of the standard awareness drills that I throw at the students and changed the variables around. Even the variants that didn’t work fabulously worked simply because they were novel.