I dust three times a week, maybe 30% of the feeders each time with Calcium only. Twice a month with D3 and twice a month with reptivite. Only thing I have done recently was forget and give him reptivite two days in a row.
make sure you are just giving a very tiny pinch of supplement dust. And I mean very tiny. Don't coat the feeders so much that they turn white. A little goes a long way. Especially if you are gutloading the feeders. I would keep to your schedule but make sure it is very little dust. The chams don't like the taste of the dust anyway. It is like taking medicine for them.
I used to have the same problem a year ago. From my research, I found that I was over dusting. If you think about it, the amount of dust when you over coat the feeders is almost equivalent to a vitamin pill for a human. That would be great for a full grown human. But your cham is not the size of a human. It would be like us taking a vitamin pill the size of a watermelon.
very very very tiny amount.
It should cover the crickets lightly.
you should not see significant change in color of the insect.
if the crickets became white after your dusting, you know for sure you are in risk of over supplementing your cham.