Snakes require certain temperature ranges to perform basic life functions (digestion/shed cycle/reproduction); nothing new to any seasoned keeper but the question is how would the snake choose to achieve that temperature if given the choice?

Over the last 40+ years of observing snakes in nature I've learned a few things and experimenting with direct lights in captivity confirms what is found in nature. -The vast majority of snakes use the sun when they have too...they prefer to reach necessary temperatures out of direct light when they are able.

The only thing emulating nature (impossible) with a 'designed' temperature zoned enclosure will do is force the snake to use what is offered to achieve the needed body temp. If you offer the proper temperatures out of the light you will see a different behavior.