[avian]

> If you're in sales then I see another tactic used instead, which is to memorize the talk

Majority of my talks in the last years have been in academic settings, but I'm definitely on the side of "over-rehearsing" on your scale. I've never done a sales talk in my life.

I guess it depends on how well you can improvise on stage. I never managed to master that. For myself, I can only "stay natural" and not be nervous when I'm well prepared.

> quiz questions, polls

I personally don't like this when listening and rarely do it as a speaker. It can be a double-edged sword. I've often seen speakers fall into the trap of asking "how many of you are familiar with X", and then proceed to spend next 10 minutes explaining X even though it's obvious that the audience already knows X very well. If you're asking questions, you should be prepared to act on the answers.

[sideshowb]

Fair enough, there is diversity of preferences in both speakers and listeners :)

I agree on familiarity polls that you should adapt content based on audience familiarity with the topic.

Whether or not audience engagement is appropriate also depends a bit on the length of the talk. It can be great for a context switch in a 45 minute talk, like a mental reset button for the audience. If you only have 5 minutes it will detract from things unless you want it to be the main focus.