In a perfect world, a retailer knows exactly how much demand they can expect, they order just enough inventory from their vendors and suppliers to completely sell it throughout their stores by the end of the given period or season. Warehouses are only used as cross-docks which streamline the supply chain from point of origin to point of sale as inventory arriving from a vendor immediately gets loaded to trucks that take it to stores. Therefore, in such a world there is no need for safety stock. However, as retailers will admit themselves, things rarely work out perfectly