The question I think very much depends on the purpose for those guns. Some people like target practice, others, like me, like to hunt, still others may be actively preparing for a life 'off the grid', planning for extreme scenarios of survival. For that last case, I think a handgun, a 22 rifle, a shotgun and a backup for each could be assumed that a person is well-stocked. For those in rural regions, a long-range rifle might be a part of that collection. To them, this provides the essential level of protection needed and nothing will get left behind when it’s time to bug out. Of course, if you’ve got a big family, that number could rise substantially, with a gun or two(or even three) per person easily justified.