Maximum stay defines the maximum stay and also the maximum number of nights the gap must have.
Note: The gap filler does not work if you use "Do not allow lower prices or shorter stays" as strategy. Also make sure the minimum stay in the SETTINGS->ROOMS->SETUP is the same or lower as in the gap fillerand you do not have manually entered higher minimum stays in the calendar.
== Example: Two night minimum stay but allow selling single nights if the night before and the night after is booked ==