This is just my husbandry method, but I tend to limit the total misting time combined for the whole day to be no more than 20 - 30 minutes. More than that, the chameleon cage easily become breeding ground for mold in my area.
I mist 4 - 5 times, 5 minutes per misting.. I do have drainage system.
And, i do not use dripper. All my chameleons get their water from lapping the dew form on the leaves.
The idea is to let your chameleon have ample enough time to drink and stay hydrated thru the day without having molds starting to grow from being overly humid.. find your balance.. usually though most people tend to agree that the minimum misting frequency is twice a day (+ a dripper)..
As far as drainage system, if you don't want the hassle to make your own, you can just buy the lll drain pan..
I just drill holes on the middle of the PVC bottom. Put the plant on the middle, so the PVC bottom naturallly bowled in the middle and water go thru the hole. I have a metal rack like this (you can buy it in Lowes/ home depot/ wal mart)
and on the bottom shelve I just put a container to contain the water drips.