The AI seems crazy about using, say, Giant Growth above everything else if
it has one in hand. It's easy to spot if it has one, because it otherwise
doesn't really attempt to attack into trades very often. However, if you
spot it and don't block into the Giant Growth it will still use the Giant
Growth to deal damage anyway. A human player very likely wouldn't cast the
giant growth then, but keep it around for the next attack.

Would it be possible to have the AI only cast a pump spell if it's for
lethal damage somehow? So that if the creature is unblocked it still has
Giant Growth for defense or pressure next turn? Or cast it only if casting
all the pump in hand would add up to lethal?