We'll not get too carried away here. After all, we're only talking about cardboard boxes.
There's a time-honoured (but curious) notion in wine (as with eggs) that one buys one's wine in sixes or twelves (curiously, both sizes get used and termed interchangeably as a "case"). Tradition is all well and good, but these aren't always your ideal quantity.
We'd also like to add the notion of "The Fifteen".
We're not the first to offer them, and it's hardly interplanetary technology, but, yes, we have cases that will hold 15 bottles.
So, if you
... then here's your answer.
A Fifteen in action
<PS: we can even get cases of eighteen, too ... but none of us can lift them, so you won't see one of those>.