There are no hard and fasts if you have a room that is cooler than the recommended air temp you will need to figure out some way to raise it and that will take supplement heat of some sort. Some choose to heat rooms (oil heaters often) some use lights or one sort or another some 2 UTHs, CHEs, RHPs there are a lot of variations. It doesn't matter as long as your temps are correct and the snake cannot be burned.
90ºF hot 80ºF cool and ambient 78-85º or thereabouts, how you get there is not super important but getting there is.
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