It certainly is and I think it is like you said, many people more or less buy supplies on demand. Although this is probably a more recent development of city dw

It certainly is and I think it is like you said, many people more or less buy supplies on demand. Although this is probably a more recent development of city dwellers and the younger generation. It isn't at all unusual that people still have supplies lasting for a month aside maybe from drinking water. The odd canned vegetables and noodles you never used for cooking can last you for quite a while. That said, to survive 72h you would only need drinking water anyway, even if you might end up hungry. If a real catastrophe hits, a well or access to drinking water would be quite helpful. The rest wouldn't be too acute at first.