There is no should. It’s your tv use the settings as you prefer.

The recommendation comes from an idea that you will more likely get content the way it is supposed to be presented with problem apps this way, and to avoid the display mode switching with ads

Sounds like that teacher should be asking it to fix the projector rather than bugging you

You have a subscription. You are neither a new nor a returning subscriber to wither service.

To a certain extent, yes, but apps like Infuse remind me of the potential that lies in moving away from the Apple mold.

What do you need turned off? You want ads off on YouTube? You need to subscribe to premium for that?

If you are having issues with a black screen for 5-10 seconds between ads and videos then your TV is switching display modes. The most often recommended settings for the Apple TV 4K here are to leave it in SDR mode by default and to allow for Dynamic Range Switching in the settings to help prevent this.