An easy tenant to live by would be a good neighbor.
An easy tenet to live by is a simple guiding principle.

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.

It falls (ha) under “Other duties as assigned” in the job description.