i use repti bark, my corns defecate 5-6 days after i feed them (they are 30 in. long) so i don't look until then. but when they do I can see it and just scoop it out. i also put newspaper below the repti bark to just roll everything up when its time to clean
i clean every 3 weeks
if you can't find anything and have to search for it in the bark, don't put a lot of bark in if you just put an inch in they'll do it on the top instead of in the bark. or just put enough bark in one part of the tank for borrowing and don't as much on the other side. or put the borrowing area in a quarter of the tank and leave the rest an inch deep where they can do it on the top, and if they do do it in the borrowing area it will be a small area to look in not the whole cage