It doesn't really matter; the whole notion is mistaken. In the long run survival is dependent on flows of food and materials, not stocks.
Survival requires continuous replenishment. Are Mormons investing in farming skills and knowledge of how to make fertilizers and agricultural equipment at various technology levels? Not to mention mining or medicine or textile-making or construction or any of the other skills required...
Most famines were too long and large for stockpiles, they were always a general avaiability and distribution problem (holodomor, Ireland, Bengal, Africa multiple times). Fun thing so, society as whole never really collapsed, not even during the Plague.
It’s not unusual for Preppers to store a year of food or more for the entire family. That absolutely would make the difference in surviving even a many year famine.
The idea that storing large amounts of food to prepare for shortages is useless is a really silly concept considering how widespread it is amongst humans and many other mammals.
Just to clarify, individual households will keep months of supplies which are often stored in the basement.