I’ve never heard of any instructors getting paid for planning, I’ve never experienced getting paid for planning,
But, I sure hope it catches on quickly!
However, I’m not sure how you could possibly have an honest account of how long it would take an instructor to do this. I’ve been teaching for over 20 years and could walk into a room cold without a plan and teach a class on the spot. But, I actually put a lot of time into planning my classes. So, it just depends….
You might be better off somehow including extra pay into their hourly wage as a flat rate.