The way I've done this is to be quite aggressive and only allow content from my channel subscriptions appear on my landing page. Anything else that shouldn't be

The way I've done this is to be quite aggressive and only allow content from my channel subscriptions appear on my landing page. Anything else that shouldn't be there gets a "Don't Recommend Channel" ding. If I'm looking for new material such as tutorials or documentaries, that kind of thing then I search in a separate non-logged in browser profile so the YT algorithm doesn't try to pollute my signed in account with junk. This has mostly worked quite well for me.