keep your search close to the enclosure; i've never had an escaped ball python go more than 10ft, and usually less.
be as thorough as you possibly can, and only move on from one area to the next once you are 100% certain the snake is not there.
even if you see a spot and think there's no way he's in there, guess what? he'll likely be there.
Turns out Dean had crawled into the broken heater right behind his tank, less than a foot away! I'm so relieved, the little bugger was all snuggled up inside there and I had to take it apart to get him out. https://ball-pythons.net/gallery/showimage.php?i=57663&c=3
Constantly trying to improve, always open to learning. For the good of the animals, education is priority.