1. A method, implemented using a computer, for optimizing TSLs (“target stock levels”) for an inventory of stock keeping units (“SKUs”), the method comprising: developing a service strategy for assigning a service level for each of a plurality of segments; identifying, using the computer, at least one logistically distinct business (“LDB”) from the plurality of segments, wherein the at least one LDB represents a flow pattern of SKUs in a supply chain determined to have a unique demand or supply characteristic; assigning the plurality of segments to a “best-fit” planning model for indicating deployment, replenishment, forecasting and review characteristics for the plurality of segments; identifying, using the computer, a probability distribution function (“PDF”) for estimating a demand process of the plurality of segments; and calculating, using the computer, a TSL for the plurality of segments based on the PDF and the at least one LDB.