100mg is the minimum for everyone but children. and in many cases, more is better.
i am currently counseling a person with basal cell carcinoma and i have them on 100mg of Lugols spaced throughout the day and a half a gram of SSKI to support the thyroid and get the skin cells sufficient in iodine.
as for more anecdotes, there are many such stories here from folks who low dosed it at first and were miserable and when i told them to go to 100mg it changed everything. this also comes from the Iodine project where they said that uptake of Iodine was sometimes inhibited and the fix was to take vitamin C or to double the dose from 50mg to 100mg. after doing some other figuring on the exposure to bad halogens like newport was talking about, i concluded that 100mg was the minimum daily dose. i take 300mg of Iodine a day.