A wide assortment offers many alternatives; a deep assortment maintains more quantity than the selected references. Both choices engage space and capital, but respond to different needs. The decision should start with the service the store wants to offer.
Many models with few units can favor variety, but quickly leaving some combinations of size and color uncovered. A more concentrated offer can support availability, but meet customers looking for alternatives. Neither configuration is always preferable.
I propose to observe unfulfilled demands and sales of the combinations actually available. A model sold little could have remained without the most requested sizes. Comparing only the total pieces therefore risks hiding the cause.
A hypothetical example is a continuous line with the possibility of rapid reordering. This condition allows for different decisions than a collection that cannot be restocked. The comparison should include supplier time and quantity constraints. The balance between variety and availability emerges when the store connects the assortment to customer needs and the resources needed to serve them, avoiding measuring the quality of the offer only by the number of models displayed.