Supplementing is not as cut and dry as, "you should be supplementing this much."
I love how people just throw out a schedule but dont mention what product they use. D3 and multivitamin twice a month isnt always the right schedule. its also not safe to just say that multivitamins should be offered more than that. It all depends on the product, the gut load and the animal itself. I use reptivite with d3 twice a week but there are other multivitamins with 10x the amount of d3. Those obviously should be offered only sparsely. The best way to supplement your animal is to research symptoms of over and under supplementing d3, vitamin a and calcium. You may find that your current schedule is not working the way it should, do some research and find an alternative. Look at what the product offers, look at what your chameleon should be getting and make an educated adjustment. Also stick to your schedule because if you lose track of what dusts you are offering and how much your offering, it makes it very difficult to pinpoint a problem if one should arise.