I think that's why a lot of care sheets advocate for 2 identical hides as well; one on the hot side and one on the cool side. That way there is an equal ratio of protection to temperature and thus the animal can even better thermoregulate. And as to whether your animal ever actually seems to adjust its temp, I think that for a captive animal the key is to give them the ability to and then let them choose whether to do it or not. That way if something comes up, we know we did everything in our power to allow them to pick the right temp.
TBH, I don't know that we'd ever really be able to tell if wild pythons thermoregulate the way we think of it....we'd have to place subdermal transmitters and monitor their locations and the temperatures there 24/7.