Heating Cages vs. Heating a Room

[msubigdawg]

I have seen that some people like to heat their reptile rooms instead of heating each individual cage. I want to hear what everyone things about both of these ideas. I personally heat all my reptile with heat tape and use a thermostat on it. I have heard that some people say that heating a whole room is cheaper but it seems like that the power bill for heating a room would be more than running heat tape attached to thermostats. I was also thinking that if you heated a room to one temp then the snakes could not thermoregulate beause their entire enclosure would be the same temperature. So I just wanted to see what everyone else did and what they thought about these two methods.
Thank you