That's my experience as well. It will only recommend videos that I assume are popular globally, and old videos from channel I've watched in the past (including videos I've already watched), until I watch enough of something new and it suddenly switches to only recommending that. There's gotta be some middle ground...

I don't understand how the recommendation algorithm seems so brittle, given that advertising is their core business, and that I am manually doing so much of the work by subscribing to channels I enjoy. A simple feed of recent updates from channels I subscribe to would be an improvement; in fact I think I mostly find videos to watch from Twitter.