Using only keywords which are googled X amount of times / month?

Broccoli Shmoccoli

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I heard that when doing keywords you should first check in google keyword planner if the specific keyword has a substantial search volume - meaning if it's searched enough times per month to be prudent to use it - and than not use it if it's not searched X amount of times per month. Now obviously there is a lot of very successful YouTube videos which don't cover searched topics. And I don't mean viral videos or videos by very popular channels. I mean just down right good content about topics which are searched mostly in YT search and / or not searched at all, but still very popular on YT.

Do you research how many times a keyword is searched for in google before you use it?