My wife's MacBook is now 34 months old. She has never used it while not connected to power. The battery basically gets used when I borrow it when I'm needing two computers at a time, maybe once or twice a month.
Her original capacity was 5020 mAh, her current capacity is 5268 mAh.
It has 26 loadcycles on it.
I did it's first and only calibration about 6 months ago, took just over 4 hours of use to drain it to the point it turned off.
My recommendation, if you're using it as a desktop and sitting next to a power outlet, plug it in. Follow Apple's recommendation for calibrating it once a month (to the letter), or when you remember to do it.
You'll have times when you want to carry it someplace else around the house or sit outside on occasion. That's good enough imho. It is a battery. It will wear out at some point in time as they all do. If her battery was to die today and cost me $100 to replace, that's $2.94 per month. Not bad when you consider what it is these batteries are running.