Article, colour and size are the item
Treating an article as one item makes stock meaningless, because the question is never how many pairs of that shoe you have but whether you have a nine in black. Each combination as its own item with its own barcode is what lets a counter assistant answer that from the screen instead of a search through the stockroom.
Size curve, not just quantity
Sales by size over a season tell you the curve your customers actually buy, which is rarely the curve a supplier ships. Ordering to your own figures instead of to a standard assortment is where a footwear shop stops accumulating unsellable extremes and stops running out of the middle. The report takes minutes and changes the next order.
Exchanges are routine here
Footwear comes back for size more than any other retail category, and the exchange has to credit, restock and re-bill without losing the original transaction. Finding the first bill by party or item takes seconds, the return restocks the exact size, and the new sale is a normal bill — so the shelf, the stock figure and the day's cash all stay in agreement.
The number to watch
Stock sitting in the outer sizes at the end of a season. Those are the pairs that will not clear at full price, and knowing which articles they belong to while a discount can still move them is worth more than discovering them a year later. The movement report by article and size answers it directly.