Personally, in regards to Addersgall, what I would like to see is that if you are in battle, the gauge keeps filling if you are at 3 (if you are not in battle and you have 3, it stops filling, and if you aren't at 3, it fills regardless of battle state). If it fills and you still are at 3 Addersgall, you just get the mp Regen and the gauge empties.

Doesn't completely punish you if you don't need healing, but you still actively use it only if you want healing.