In my opinion, the greatest sin of all is that we have spent thirty years developing forecasting processes that are largely not used or trusted by the organizations that they serve. In order, the seven sins of demand planning are:

Sin #1.  Not Using the Statistical Forecast to Drive Continuous Improvement

Sin #2.  Only Owning Part of the Forecast

Sin #3.  Misuse of Downstream Data as an Input

Sin #4. A Project not a Program

Sin #5.  Not all Items are Created Equally

Sin #6.  Forecast with the End in Mind

Sin #7.  Arrogance.  Not serving the Organization.

For full commentary on each sin, visit the author's Supply Chain Shaman blog.

Source: Supply Chain Shaman