When I had RAI ten years ago, I was told to flush twice, not that I needed to have a bathroom all to myself. So I assume that suggestion was designed to get rid of any potentially lingering traces of RAI in the toilet bowl. I also assume that rinsing out the shower/tub/sink after each use would help in the same way. (During the first two days or so, any RAI that did not get into our thyroids is eliminated via urine and sweat and saliva). Most of the suggestions we get, therefore, have to do with this particular period of time unless we have very small children about.
I hope this helps,
Bobbi — NGDF Online Facilitator