Why Mixed-Size Packs Outsell Single-Size Buys
Ask a reseller where their dead stock comes from and the answer is often the same: the wrong sizes. A parcel bought cheap on paper turns expensive on the rail when it is stacked with the sizes customers rarely reach for.
This is why the structure of a pack matters as much as its price. A mixed-size pack that weights the middle of the curve — where most real bodies sit — sells through evenly. A single-size buy, or a pack skewed to the extremes, forces you to find a home for the leftovers, usually at a discount that erases the original saving.

A typical menswear curve across S to XXL runs something like one, three, four, three, one across a run of twelve: the middle two sizes carry more than half the units. The exact shape shifts by category and by market — a fashion-led fit runs smaller than a classic cut, southern European markets skew smaller than northern ones, and a tourist-heavy location sells a broader spread than a neighbourhood shop — but the general shape holds nearly everywhere, and a pack that inverts it is buying you a markdown.
The arithmetic is worth doing explicitly, because it turns an instinct into a number. A hundred pieces at €20 is €2,000, and if the pack is balanced you might sell ninety at full price and clear ten at half. That is €2,000 of cost against sales you planned. Take the same hundred pieces at €17 — a price that looks a great deal better — in a pack where thirty-five pieces are sizes you barely sell. You clear those at half price or worse, and your cost per piece actually sold at full margin is now higher than it was in the dearer pack. The unit price fell and the real cost rose.

The ideal ratio varies by category and market, but the principle holds everywhere: buy the sizes you can actually sell, in roughly the proportion you sell them. A balanced run turns over as a unit; an unbalanced one leaves a long tail of markdowns.
Ask for the ratio in writing, before the invoice, and ask for it as a table by size and colour rather than as a description. "Mixed sizes" and "full size run" are not specifications — they are adjectives, and they cost buyers money every season. A seller holding the stock can produce the real breakdown in minutes. If the answer is vague, the honest reading is either that the seller has not counted it or that the count is not flattering.

None of this makes a single-size buy wrong in itself. It is exactly right when you are filling a known gap: you sold out of L in navy in three weeks, you know the demand is there, and a hundred L in navy is not a gamble but a replenishment. The mistake is not buying one size — it is buying one size without that evidence, on the strength of a price.
There is one more thing the size curve tells you, and it is about the seller. A parcel that has already had its best sizes picked out is a parcel someone else has traded through, and the price should reflect that it is the tail rather than the run. That is a perfectly reasonable thing to buy if you know what it is and pay accordingly — plenty of good business is done in exactly those goods. It is only a bad buy when it is sold to you as a full run.
On VESTRA, listings state pack size and size ratio up front, so you can judge a parcel on the sizes you will move, not just the price on the label.