If graphene is used for heating, it is equivalent to holding water in a bamboo basket, which consumes a lot of electricity and produces extremely weak heat. If someone tells you that graphene is more energy efficient, it's not true. It can only be said that the main body of heating is other high-resistance materials, not graphene, which is just to satisfy people's yearning for high technology.
In fact, if graphene is used as the main heating material, it will get twice the result with half the effort, because it is an excellent heat dissipation material, and the heat generated after the current passes is extremely low.