My brother who has young kids did the thing where you can make a combined playlist with me. He has indeed kids music littered all over in the shared playlist but moreover he also listened to a 100 track audio book on Spotify (which was not a great experience since it was published as an album and did not have bookmark support). The algorithm thought: oh he must REALLY like that album because he keeps on playing tracks from it, and so chapters from this book were also in our combined playlist