Same money, more real food. The move is simple: buy the staple, then use the whole thing.
Walk two aisles. In each one, pick the item that keeps feeding you after the first meal.
Shops once a week and makes it stretch. One roast chicken turns into dinner, two lunches, and a pot of stock before the bones hit the trash.
Two aisles, two staples, days of real food. The move repeats in any store: buy the whole-food staple, then use all of it before you buy more.
A convenience item is one meal, then it is gone. A whole staple keeps going: the chicken feeds you three times and its bones make stock, and a bag of potatoes covers sides all week.
Same few dollars, spread across more real meals. The whole move is this: buy the staple, then use all of it.
No math to it. Each one just keeps feeding you after the first meal.