"There are known knowns; there are things we know that we know.
There are known unknowns; that is to say, there are things that we now know we don't know.
But there are also unknown unknowns – there are things we do not know we don't know."
United States Secretary of Defense, Donald Rumsfeld
Author's note, all frameworks are inherently flawed, so apply them wisely. The utility of a framework is always dependent on the individual problem at hand.