Always plugged "good" for MacBook battery?

We know it gets to a point where a MacBook's battery gets full and charging stops even when the device is still plugged to the power adapter. This way, the device uses the power that the power adapter delivers, not from the battery. So, during this time, the battery doesn't drain. I guess it's safe to say that, the longer the battery is fully charged and the device plugged (or you plug the device every time you use it), the lesser you affect the charging cycle. This is the case for me on most days.

My MacBook Air is 10 months old and, as shown here, had an average of only 14 charging cycles per month of daily use. Is this a common/average case? Is this a good way to manage battery longevity? Should we advocate plugging notebooks while in use whenever possible?