Those saying it takes 8+ drinks to break even either aren't doing the math correctly, aren't accounting for the wide variety of non-alcoholic drinks covered, or perhaps a bit of both,
At $12/drink (which is a rounded average across various sorts of alcoholic drinks: the average cost for beer alone would be lower, wine and frozen drinks are in that ballpark, and cocktails higher) you'd need to average 6 drinks/day/person though that only takes into account alcohol. Cheers also allows unlimited soda, bottled water, specialty (meaning anything but the most basic, available at the buffet/MDR) coffee, milkshakes, energy drinks, and a couple of others, which must be factored in as well, bringing down the number of alcoholic drinks to hit the break-even point.
You can use a calculator, such as this one, to help you determine if the package would work for your cabin.