Systems and methods for identifying, assembling, and transmitting content are described in the illustrative context of electronic program guides and program channels. Data is received over a network from a first user terminal that enables identification of the first user. Program information for a digital program is accessed. A determination is made as to how many interstitials are to be presented during a playback of the digital program. A prediction model is selected and executed to generate predictions of user responses to one or more placements of program interstitials. The user response predictions are used to determine positioning of interstitials with respect to the program. The interstitials are enabled to be displayed on the first user terminal in accordance with the determined positioning.