Don't worry about it. Just because the Magsafe is plugged into the Mac, doesn't mean it's charging the battery.
About 1 hour after the Magsafe LED turns green, the battery stops charging. After that the Mac is powered just from the Magsafe. The battery is isolated from the system. If you leave the Mac like this, after a few days or weeks the charger will add a little top up charge to the battery.
So leaving the Mac plugged into the Magsafe is no different to unplugging it. The charger is very smart and will look after your battery as well as possible.
Read the Apple article carefully. It does not say do this to keep the battery healthy. It says "The battery needs to be recalibrated to ... keep the onscreen ... display accurate and to keep the battery operating at maximum efficiency"
Calibration is more about accurately estimating how much charge the battery can hold. It's like having a car with an inaccurate gas gauge, and a tank whose size varies with time. The only way to really know how much gas the tank can hold is to empty it completely, and then fill it up noting how many gallons it takes.
The battery on my Macbook is 3 years old, 400 plus cycles and it's never been calibrated. It's still at 90% plus capacity, and it still runs the computer for 3 hours or so.