The consensus here seems to always be leave in SDR and use match content, but I’ve had no issues with leaving Dolby Vision on all the time. SDR content like youtube and TV shows that were never mastered in HDR look 100% fine to me. Part of the Dolby Vision spec is that it forces your TV into it’s most color accurate settings so why wouldn’t I want that as well? Using an LG C2 by the way.
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