Personally, the majority of my Home page are videos from my subscribed channels. I get the occasional suggestions for related content from other channels, but I'd say 8/10 times the suggestions are good ones for me.

My typical usage is:

* Go to Home page * Add highly relevant videos to my Watch Later playlist * View the videos from Watch Later, like/dislike as appropriate * Rinse and repeat

I'm trying to give Shorts a shot. I particularly like them for viewing podcast shorts, but I've noticed the suggestions are taking a longer time to give me 'relevant' videos. Some of the Shorts are totally random, while others are from my Subscribed channels. I make sure to like/dislike as appropriate, and I've noticed a slight improvement in a week's time.