Usually they lead to entirely different parts of the building. I had one once that led from the living room to the back bedroom.

It is a special type of room that allows you to travel through a building without intruding on people in the other rooms. Except of course for the house I lived where you had to go through the master bedroom to get to the only bathroom. Or the house I lived where the only bathroom was the only way ...

It enables contactless joysticks that last longer, by my understanding