A server system sorts a plurality of sessions for multiple users of a media-providing service into a plurality of groups by applying one or more sorting rules to one or more session characteristics for the plurality of sessions. The server system divides respective groups of the plurality of groups into respective pluralities of clusters using a machine-learning algorithm. The server system tracks user interaction with a client device during a user session and identifies the user session as belonging to a first cluster of the pluralities of clusters based at least in part on the user interaction. In accordance with identifying that the user session belongs to the first cluster, the server system personalizes content for the user session using one or more content criteria associated with the first cluster.