Behemoth growth

For Deezer to grow as Spotify, it's gotta make for behemoth (recommendation algorithm) performance.
- Spotify's algorithm is heavily weighted by listening time (percentage of time listened)
- It recommends users songs that have high listening time, and that are relatable to the user's song cluster
- Spotify uses (implicit) song metadata to put songs into song clusters
- It finds songs for users by adapting to the individual's taste through implicit engagement