Apple says they "do not recommend" leaving a notebook plugged into mains power all the time. But I cannot use my MBA with an external display, external keyboard and trackpad *unless* I specifically put it in clamshell mode AND keep it connected to mains power. Presumably, in this configuration, the MBA is constantly charging, which surely contradicts Apple's advice about not keeping it plugged into mains power all the time. Does anyone definitively know if running the MBA on mains power is okay for the health of its battery? Is it simply that I should let the battery discharge fully by itself once a month but otherwise hooking it up to mains power does no harm? If so, why does Apple give this misleading advice?