Hmm, yeah, I'd never given this much thought. I think the only time I've written f/f/f was when it was a case of three genderswapped boys; so, you know, I took a slash ot3 and made it suit my tastes a bit more.

I've always categorised anything that happens to have a man in it as het/femslash together, sort of. Again, not something I've given a great deal of consideration in the past!