A promotional message may be provided to a first portion of a group of users. A first watch time may be identified based on an amount of time during a period of time that users of the first portion view the video content items after being provided the promotional message. A second watch time may be identified based on an amount of time during the period of time that users of a second portion of the group view video content items where the promotional message is not provided to the users of the second portion of the group. A difference between the first watch time and the second watch time may be calculated. A determination of whether to provide the promotional message to a subsequent user sharing one or more characteristics with the group of users may be based on the difference between the first watch time and the second watch time may be made.