Your spare parts management system must involve a clear, unambiguous labelling system. This can include a grading system for judging stock levels. Two common methods are the ABC and XYZ systems.
The ABC system grades parts by financial value. ‘A’ parts cost the most while ‘C’ parts cost the least. This system also assumes that of all the different parts you stock, ‘A’ parts will generate the most revenue. This means your shelf space will hold mostly low-cost ‘C’ parts with just a few expensive, but crucial, ‘A’ parts. ‘A’ parts need more frequent cycle counts, though.
The XYZ system is similar, but grades based on demand. ‘X’ parts are sold the most, etc. With this setup, you’ll have many ‘Z’ parts at low stocks since they sell infrequently, and larger stocks of just a few ‘X’ parts that get continually replenished due to sales.
An ideal inventory management system will use both of these to optimise stocks of spare parts based on how much revenue they’re expected to generate and how often.