That may be why my recommendations seem to work so well, unlike a lot of other commenters on this article.

For posterity, I have a little under 1000 tracks saved from 200 or so artists (of which I am following around half), around 50 favorite album playlists and about as many "I should give this album a listen" playlists.

So not really a huge collection in absolute terms. It is very much focused on hard rock and metal, though.