Lets simplify this whole calculator, is it wort it, BS...
Will you put away on average 10 cocktails or 13 beers a day, every day, for the entirety of your cruise? (or like a 5/7, 3/5 ratio, something close?
Then you'll get your money's worth from Cheers!, and the bonus of soda and other drinks in addition.
Always get a bottled water with every cocktail you order, take it back to your room, save it for later.