Consider, for example, actions for the use of bicycle lighting, promoting your company's products, drawing attention to pickpockets or encouraging passers-by during a crisis such as Covid.

Once the promotion or campaign has ended, you can simply replace the gobos and possibly move the projector to another location.

By using a twilight or time switch, you can only show the projection at times when you want it.

Example: there is a nuisance with bicycles being parked everywhere during busy evenings.
To prevent the bicycles from being placed in places where this is not allowed, you can project a message on the floor at those times that makes it clear that the bicycle cannot be parked, or vice versa that the permitted places are indicated at that moment.