If you and I both pay $10/mo to listen to Spotify, and we are the only subscribers. If I listen to 1 song by Sabrina Carpenter, and you listen to 99 songs by Taylor Swift. Then of our $20 (after Spotify's share) 1% of the money will go to Sabrina and 99% of the money will go to Taylor. Because Taylor was played 99x more than Sabrina. Even though for both of us as users, our respective artist was 100% of our listening.

It doesn't calculate your amount of listening and determine the payout based on that. All listens are pooled together and all subscription money is pooled together. And the payout is determined based on that.