Don't 'rarely' use Medica II. That's a habit you don't want to have. Medica I is just an AOE Cure I.
I used to think exactly like that, until I got into the Vault. And Medica II is AMAZING for Midgar in Keeper of the Lake.
Also overhealing is natural when you use Regen/Medica II.
Generally speaking, if you heal someone that barely needs it, yeah that's over healing for sure. Necessary times where you have to spam healing - this can't be helped.
