In almost every facility on earth (and I don’t think I am exaggerating) there is a place in which equipment and spare parts are kept that someone thinks is important to keep but not part of any system of control.
Spare parts inventory optimization is great. It helps companies identify where they are holding too much spare parts inventory and correct those holdings to reflect their expectation of current needs.
Usually when people (myself included) raise the topic of the cost of inventory, we talk about the financing and management costs of holding inventory. However, with spare parts, many people consider these costs to be either conceptual or "sunk" (that is, a cost that cannot be recovered). It is this view of spare-parts inventory costs that prevents many companies from taking action to review their inventory and particularly review their spare-parts inventory-management processes.