My dad died last month and I'm heading shortly to my mother and her house full of 44 years worth of STUFF. Much of which is, as you found with your Gran, also the accumulation of 100+ years of a family of farmers. Mom's current plan involves moving back to her childhood home -- which is already full of its own STUFF and does not require any of her STUFF to go with her, except for things like clothes.
It's a 4-bedroom, two-story house with an attic and a full basement. I'm doomed.
There are entire cabinets in the basement filled to overflowing with glassware from the Depression and prior. And post, too, for that matter. Every room in the house is full of antique furniture and knick-knacks and yet more glassware. Things from my various great great grand somethings, and from this homestead and that old farm. And while my mother at one time knew where each and every piece in her house came from, the not-as-mild-as-she-likes-to-think stroke last October has played havoc with that knowledge.
So I am about to be confronted with a houseful of stuff, much of which will be antiques, some of which will be 'heirlooms' (things which we cannot sell upon pain of death, at least not while my mother is still living), some of which will be WTFery -- and exactly 50% of which my mother is going to try to pass off to me. (Thank the gods I have a sibling who will be saddled with the other 50%).
I will clearly not be allowed to apply your awesome rubric while standing amidst the STUFF in its natural habitat. But I most assuredly will apply it once the migration has occurred and I (in my tiny little home) am inundated-unto-drowning in the STUFF that is my birthright as my mother's daughter.