I have a microscope and I run fecals on all my chameleons once monthly. I don't treat just to treat. Panacur was first given empirically when introduced to chameleons, it was not designed specifically for them. It can only target adult stages of nematodes.(which is actually a benefit). That is why we use it now instead of Ivermectin. That drug was killer. It would cause toxic shock. So, I would not administer the drug just to administer under the vail of being on the safe side. If you run fecals, just look for eggs or adults. If they are present, then treating is feasible.
This is just my opinion. Some keepers do treat annually. I have just found better results with my methods. They have obviously found good results with their methods.