Just out of my ignorant manly curiosity...it seems like you're saying a shiled requires a pierced nipple...is that correct?I'm not sure if it's normal for all sheilds, but her's does. I'm guessing she takes private jets and doesn't have to be scanned for metal at airports?
my guess is you wear it when you will not be wearing a blouse or bra. Probably doesn't include trips thru the airport or other metal detectors.