I recall the rule being as long as there is 30 seconds of a track there, it will count.
They don't and they never did.
Quote:
The updated Billboard 200 will utilize accepted industry benchmarks for digital and streaming data, equating 10 digital track sales from an album to one equivalent album sale, and 1,500 song streams from an album to one equivalent album sale. All of the major on-demand audio subscription services are considered, including Spotify, Beats Music, Google Play and Xbox Music.
