would this indicate a matriarchal social structure? Perhaps because she lays in the cock bird's favorite nest, the safest one that's been approved by the leaders of the flock. oTwo things, I believe, but I'm just basing this on years and years of observation.
First, the "clutch" is made and if one hen's eggs get put into that clutch, if someone goes broody, their DNA gets passed on. In other words, nature's attempt at preservation.
Second, this has something to do with pecking order. If the Queen Bea uses a particular box, they all seem to want to use that box too.