I use Spotify for training, either running or at the gym. I have created special playlists for it or put on ready-to-use playlists as favorites and downloaded the titles. During training I start a certain playlist, and after four or five songs another song suddenly appears (in the middle of the track). This is not a song I have in any playlist, because sometimes they are songs I would never hear myself. Spotify also ignores in this case that it should only play downloaded songs without a WiFi connection. It' s really annoying.