The Buff Orps never gave up, ever. My Wyandottes never went broody long enough. Daphne only sat 2 weeks-- not nearly long enough, and Zinnia never spent more than a night on the nest. Can't count that as broody.
I probably wouldn't let a unproven broody hen sit on the eggs unless I wasn't...
That puffing up is a sure sign in our coop. I only had two Buff Orps, but one went broody almost all the time. It got so bad that if she laid an egg I got suspicious! Then of course, the other BO and her BFF would surely decide that was a grand idea and go broody herself. They never plucked...