If you are going to ask the question, perhaps it is better asked, if you are dosing iodine, how much, what size is the tank, what brand, why and what are your results from dosing.
Iodine is contained in salt mix and as pointed out, with proper water changes, you should not have to dose it. Also as mentioned, unless you are testing for it, it should NOT be dosed at all.
So Mr. Brightwell himself (a manufacturer...) suggests everyone dose a drop a day eh?
I wonder how the math came out when he figured out how much $ he would make if everyone did that..lol