The tell is coverage rather than age. A product with a year of cover is dead by arithmetic even if it sells one unit a week, because that is a year of cash standing still, and a store carrying several of those is financing a warehouse rather than a catalogue.
The instinct to wait for full price is usually the expensive choice. Every month of waiting adds storage and delays the reinvestment, so the honest comparison is what the stock realistically fetches now against what it will fetch later, minus the cost of holding it in between.
Preventing it is mostly a buying discipline. Ordering to a target cover rather than to a price break, and reviewing coverage per variant rather than per product, catches the sizes and colours that quietly stop moving while the parent product looks healthy. A periodic count on the inventory count sheet confirms what is really on the shelf.
