Battlefield Spell-scripting bug?

[Finalgenesis]

Seems as good a place as any to ask this, can any vets share their observation on AI mage gem spending behavior?

Do AI stick to bare minimal gems to keep fatigue under 100? Generally I see the opposite, AI tend to use a lot more then I expected even when I plan for extra gems to cut fatigue already, resulting in me throwing my hands in the air and just dump a lot of extra gems on them. Trying to cast more then 1 big or 2 smaller gem spell seem to be all I could do economically gem wise. (eg. 3 gems on a caster that has just enough path to cast a 100 fatigue 1 gem spell and script to cast twice seem to work... usually)

Vaguely (I haven't paid much attention to it) I think I remember my mages sometimes using gem to cut fatigue even if the end fati stays under 100 after cast, is this true? If so, when generally will AI choose to use gem: >60 fati? >80 fati? size of spell?

I also recall mages using more then 1 additional gem over the minimum even if 1 additional gem can cut end fatigue to less then 100 already.

Anyway, any observations would be welcomed.