Halides like bromine and fluoride have a similar structure to iodine and may be absorbed in places where iodine is meant to be taken up. We need to keep iodine flowing throughout the body to make sure it is absorbed and that the halides are not absorbed. This method of increasing saturation to prevent uptake of harmful molecules is the same idea behind taking emergency doses of iodine.
Iodine gets distributed throughout the body and so it could take some time before all iodine levels are restored. The thyroid’s iodine needs seems to be satisfied first. Regular doses of iodine is a more effective way to stay protected especially because you will enjoy the numerous benefits of total body iodine supplementation.