Jazzepi:
But problem is that you can just script for 5 turns, in late game when you have expensive spells researched masters will cast them, even if they are totally useless [for example enemy slowly routing]. And casting 100+ fatigue spells every turn is exhausting. Especially when you add Phenix Pyre to that you have nice effect
Baalz:
Many nations can access higher level battle spells only through communions, so hard to avoid them or use just low level spells.