They all do their "own thing" according to what they need, and they didn't "read the manual".Assume they move more at night, in the dark, when unobserved.
Many snakes sit still when watched (as a defense), but if you've been sitting still watching your snake & waiting for him to move & thermoregulate all this time, you
may have a bigger issue than he does? ROFL. I'm just teasing......but stop worrying. BPs are not very active snakes to begin with. I can promise you that my rat
snakes move around a whole lot more, as do many other kinds; BPs are ambush-predators, & if they're "out and about" in the wild, they're putting themselves at risk
of being a meal for something else. Just make sure his temps. are correct (& accurately read).