yuri -multiple_girls has 176 pages of things in it, all of which seem to contain multiple girls.
I checked yuri solo just to see if there were any counterexamples -- there are some in there, but they all either clearly have two girls, or are masturbation, which I don't think qualifies as yuri...?
I guess the main question is whether a hypothetical image of one girl in a position that clearly implies a yuri relationship is going on would get the yuri tag. I can't find any such images myself, and I'm not sure they'd be intended to get it... are there any images with just one girl that should logically get the Yuri tag, or not?
EDIT: Hmm, post #455946 seems like a valid counterexample, in that it clearly has only one girl and yet clearly implies yuri is going on... still, I guess I'll leave this post here to point out that multiple_girls is underused.
Is there some easy tool that lets someone rapidly go through a list of images from a search, and apply an additional tag to things in that search with one click, for cases where one tag (or two tags, together) almost always imply something, and where it could almost always be easily seen from the image preview?
Updated by jxh2154