what brand are you using?
what type of chameleon is it?
does it have access to the outdoors?
what type of UVB lighting do you use? How frequently is it changed? does it pass throught anything, like plastic or screen?
what do you gutload with?
D3 is necessary for formation of bones. D3 from supplements can build up in the system and cause damage (Excess Vitamin D actually causes ABSORPTION of bone, and causes mineralization of organs). Vitamin A also figures into this because vitamin A and D3 are antagonistic to each other.
Rep-Cal has 400,000 IU/kg of D3 whereas Miner-All (I) has 4,400 IU/kg of D3 and I think 150IU D3 in Nutribol (which also has Vit A so be wary of using this very often). That's a considerable difference in D3 strength.
Using Rep-cal twice a month is usually sufficient for a chameleon raised in doord under acceptable UVB lighting. Using it twice a week wouldnt be a good idea, in my opinion.
Whereas Miner-all (I) could be used every week, even twice a week, for this same chameleon. Twice a month may be insufficient.
More info on supplements:
https://www.chameleonforums.com/blogs/sandrachameleon/65-supplements.html