[August]

I guess it depends on the survival situation you're talking about. Prepping for natural disasters is not the same thing as trying to prepare for the fall of civilization. With natural disasters you are just trying to outlast the rescue/recovery clock. 30 days food and water would cover you in almost any natural disaster.

Surviving the fall of civilization is another thing altogether and even that covers a wide range of scenarios from a gradual societal collapse all the way to a nuclear war nightmare with every possible situation in between so learning how to turn ones poop into fertilizer might be a useful thing to know.