Why pay to heat a room you don’t use?
Unless I have company, I keep the vent in my spare bedroom almost closed so that most of the heat coming up that duct makes its way into my bedroom rather than one that’s unoccupied. I also keep the door to the spare bedroom closed.
Another door that I used to not bother closing was the one to my closet. But then one morning by accident I shut the door and realized my bedroom was warmer that night. Turns out the closet isn’t as well insulated as the rest of the house and when the door was open it allowed cool air into the room.
Once I started closing the closet door, I was able to lower my thermostat a couple degrees at night yet still stay warm.