One in my house. Used it as our primary source of heat for about 10 years until wood got too expensive. That was 25+ years ago .Haven't used it in at least 15 years.
My parents house had two, one in the family room, one in the living room. Used the one in the family regularly, used the one in the living room just once in the 53 years my parents lived there. That was Santa's fireplace since the Christmas tree was in the Living room. I sold the house to flippers, they took the fireplace out of the living room. They hired a staging company, who put a FAKE fireplace where the real one had been!