A question that many ask is if they do need a window sensor on every window. Window sensors are meant to trigger alarms when a window is opened or forced. This means that there is no reason of installing door sensors on door that cannot be opened or forced. Surely a window on the first floor is more likely to be used by an intruder than a window on the 5th floor.
At the end of the day, it is up to you and your team to decide on which windows the alarm should be opened. It is not necessary that all windows are covered but our suggestion would be to be protected as much as possible by enabling the alarm on all the accessible windows.