Is this normal spell-casting ai behavior ?

[Boron]

I fought as Pythium against Pangenea . Pangenea had a medusa + 100 living statues .
I had the idea to script my theurgs to quickness , false horror x4 , cast spells .
The plan was just to generate a "meat shield" with a few false horrors in the hope that the theurgs cast after this combat spells occasionally too .

My theurgs only casted a few buffs after the 5 spells and then continued with false horrors + phantom warriors only .
Is this normal behaviour ?
They could have casted at least mind burn too which would have helped a lot agains the living statues .