Guidelines on the interaction and content design of visual displays inside elevators

I found the question What makes the elevator experience so awkward? rather interesting, but for practical purposes thought it was better to focus on one aspect of the experience that designers have tried to improve by providing some visual displays inside the elevator.

I assume that due to the physical and technical design constraints, the position of these displays are located usually above the buttons for the floors inside an elevator (even though some elevators don't have them inside) or on the wall near the entrance to the elevator.

Since it is impossible to determine the amount of time people may be waiting outside for the elevator, or the amount of time that they might spend inside the elevator, how do people determine what content is presented on these visual displays and how long contents are displayed before they are changed?