6:12 is more or less builder spec for tract houses. I’d think it’d take 10:12 for the weight of a deep snow to break it loose and slide off. It’s the thought behind those A-frame chalets with the roof running to the ground.
There’s the minimum codes, and then there’s good sense!
I do wonder what a good sense difference would be for asphalt shingles vs. metal. There are some pretty frightening scenarios that create the perfect storms for roof collapse.
Maybe what homeowners need are those recreational cable thingies that are set up at fun parks for people to play Tarzan. Mount ‘em on the trees or poles on each side of the house, and go sliding above the peak, shovel in hand. Weeee....