From the week that just past after commencing iodine dosing, I swear by it now. Some of my SPS corals had STN at the tips and looked beat up. After discussing with some reefers from a UK reefing forum, I dosed Coontinum's Iodine solution everyday for a week (10 ML per day).
STN stopped, polyps came out, LPS coral tissue became more inflated and colours and growth bounced back. Carbonate consumption shot up as evidenced by the drop in my daily dkh test results. I had to redial my calcium reactor to compensate.
I would suggest once everything is back on track from such an STN episode due to a lack of iodine, a maintenance dosage should be done with say 2-3 dosages per week.