they are not every sister's head, BUT that it's for organization's sake
nbd: The basic premise is, that the males have the teaching role, the firstborn males in the family, tribes.
whenever a lady has to step in, she covers her head. no big deal all ladies had their head covered all the time back then in bible writing times. so:
when "sisters" now have the major teaching role in the comments on wt material, at least they should cover their head. but as 1 Cor 14, 1 Tim. 2. clearly states, be quiet for a change to at least give a veneer to the claim that wt is a bible based organisation.
Eve, assumed to be in the nude, should have had a headcovering, because she spoke for the small congregation she was part of. or call her husband and then take the covering off.