A nice activity, or maybe just a thought experiment, from Nick Robinson at ELT Jam taken from the Pareto Principle. Apparently, the Pareto Principle says “for many events, roughly 80% of the effects come from 20% of the causes”. So here's Nick's challenge:
Grab the nearest ELT coursebook. Open up a lesson and look at the lesson objectives. Bearing those lesson objectives in mind, read through the lesson and start crossing out (in pencil, of course!) anything that you don’t consider 100% essential to helping the student achieve that objective. Nice warmer activity? Sure, but we could probably skip it if need be. Hm, interesting text used as vehicle for the grammar point? What if we just showed a few examples in individual sentences instead? Ah, sweet, some video input! Shiny. Actually, though, it’s not really adding anything that I couldn’t supply with some good old-fashioned acting at the front of the class. Keep going and see if you can get rid of 80% of the content. If you think you could get the learner 80% towards the lesson objective, using only 20% of the content, then that’s a win for Pareto!
I would say try this with your own materials and writing as well. Someone somewhere once said writing is all about killing babies, meaning editing out all the fancy doodads and trills and frills and clever allusions that pretty things up but don't actually help the reader at all.
I think when it comes to teaching that there does need to be some entertainment and engagement. But I suspect that too often we let the fun get in the way of the teaching and learning. 80% may be too harsh. Or maybe we need to realize that engaging learners is a key objective, essential to helping the student. But I'm sure that a large percentage of what happens on the page or in the classroom is not vital to teaching students.