For the past few years Spotify’s Discover Weekly has been the main way I discover new (to me) music. Secondarily I guess just from browsing the related artists of the ones I already listen to. Looking for other strategies inside or outside of spotify.
I do similar, it definitely makes spotify better for discovery. I read an article a while back on their algorithm and how it utilizes playlist-ed songs. I wish I was as organized as you, I pretty much go in one playlist until it gets too annoying long then “archive” it into a 1 or 2 year chunk.