Whenever I get files in higher quality than you'd normally get from e.g. YouTube Music or Spotify. Currently I'm at a just 9.2 GiB library, but whatever, I don't listen to music too often anyway

Lately ive been getting a lot of new music from rateyourmusic.com . I look up an album i like, find some themed lists featuring it that aound interesting (a lot of the lists are like "things i listened to this year", i ignore those), and will hop from list to list as i see interesting looking albums.

I highly recommend Hype Machine for properly new and sometimes unexpected music. Downside is that you need to sort through some stuff you might not enjoy but upside is pretty solid when you find a new artist! More organic than any of the prediction-based discovery apps.