Opinions on heating

[CosmicOwl]

I provide heat to my snakes via a UTH, and have always followed the general rule of heating a third of the bottom of the enclosure. However, I'm wondering if this is really practical. For the purpose of this discussion, I want to discuss only temperate region snakes. I realize that a lot of snakes from tropical regions(and deserts) have more intense heat and humidity requirements so they should be left to their own conversation.

Back to the point; is it necessary to heat a third of the enclosure? A lot of times, this recommendation seems to be mentioned in hand with the minimum spatial requirements for the snake. "A 20 gallon tank is fine for a corn snake, but remember to heat a third of the tank floor." In this instance, you'd have to heat a third of the cage, because an adult corn snake would take up about that much space. But what about a larger cage? If you have an adult corn snake in a 60 gallon tank, is it even beneficial to heat up a third of the tank floor?

My thought process is that even in a massive enclosure, a snake would be able to find a warm spot in minutes. I also wonder if keeping the majority of the enclosure cool(low to mind 70's) with a smaller area of heat, would mimic the snakes natural behavior to seek warmth. As long as the snake has a warm place to hide(possibly a basking spot, if it's a diurnal species) and digest, is it necessary to heat up a large portion of the enclosure? Or do you feel that a steady thermal gradient is required?