My understanding is that companies rarely track inventory per piece directly, since it’s much easier to track box/package size as dictated by their distribution standards.
So if a company runs out of small boxes, they can’t just undersize the amounts in a medium box without totally screwing up their inventory management, because their inventory management expects a certain amount in those medium boxes.
Allegedlys.
There’s a reason the Xanatos Gambit (CW: TVTropes) is named after him.
Cross my heart, smack me dead, put a lobster on my head