@ repoe
I use macro's primarily on my tank to stack multiple abilities on a single macro, namely abilities that are off the global cooldown. That streamlines my rotation while having as few abilities on the action bar as possible. Another useful aspect of macros is using it to stack abilities that you would only use when synced to a lower level. An example being to heal on a CNJ/WHM when I have free time i can spam some damage like stone/stone II, so I have them all on a single macro where if the strongest isn't available due to level sync it will use a lower level spell that is available instead.