Is it? It always seemed like more of a cash flow question to me. You buy whatever you are going to use, put it at the back of the shelf, and grab the thing you bought 3 months ago. Clearly, we're talking about only non-perishables here. But the goal of a 3 month supply is not a hoard in a closet that is pulled out in an emergency, but a flow of goods through your normal life. You build up to the supply a bit at a time, so it is never a full 3 month purchase, but a slow steady growth until you hit your goal.