In my experience, Spotify generally picks 20-40 top songs from each genre and recommends them to any listener that has showed interest in that genre.
To a listener new to the genre, this yields a pretty good hit rate and the perception that Spotify is great at recommendation, but after spending any reasonable amount of time listening to the genre, the same 20-40 recommendations get stale and Spotify is completely unable to surface relevant songs from deeper in the genre catalog.
To a listener new to the genre, this yields a pretty good hit rate and the perception that Spotify is great at recommendation, but after spending any reasonable amount of time listening to the genre, the same 20-40 recommendations get stale and Spotify is completely unable to surface relevant songs from deeper in the genre catalog.