Yes. The more you use the earth as a heat sink, the more stable the temperature. Where most tortoises come from - in the tropical regions, the temperatures day to night are far more stable as well. Those that come from more of the fringes of the tropics or where temps vary more, tend to be the tortoises that use burrows more. So under a rock shelf, under leaf litter, dug in a pallet under a bush, and certainly in a burrow, the temperatures are amazingly stable.
