Methods, apparatus, systems and articles of manufacture are disclosed to calculate video-on-demand and dynamically inserted advertisement viewing probability. An example apparatus disclosed herein includes a category manager to identify a targeting strategy for advertisements associated with media presented in a first set of households and a second set of households, a probability engine to calculate a baseline viewing probability for a non-time shifted presentation of the media in the first set of households and the second set of households, and in response to identifying presentations of the media having a subsequent temporal sequence from the non-time shifted presentation, calculate corresponding time-shifted viewing probabilities of the media for the first set of households and the second set of households, and an imputation engine to generate viewing probability trend information of the media for the first set of households and the second set of households, the viewing probability trend information based on the respective time-shifted viewing probabilities, and adjust the targeting strategy to reduce wasteful targeting of the advertisements, the adjustment to select one of the first set of households or the second set of households to insert the advertisements based on the viewing probability trend information.