A goal without a Plan is just a Wish - Antoine de Saint-Exupery (1900-1944)
Plans are strategies, strategies are a hypothesis, a hypothesis requires tests to assess their validity. Without a Plan, you have no means of knowing what Done looks like, until you run out of time, money, or patience of those paying you to produce value. Since all projects operate in the presence of uncertainty (reducible and irreducible) estimates must be made for the decision necessary to follow the Plan needed to reach Done with the needed capabilities, for the needed Cost, at the needed Time.
