While playing Arcade and Custom Content I have noticed that the AI builds ballistas pretty often even on maps when there are no airports/flying units. This frequently occurred in arcade mode in the "Hard" difficulty which gave me an opening to win. (idk if arcade difficulty just affects the amount of $ the AI has or also unit selection). I can maybe see certain instances where its worth building a ballista when you can not afford the Trebuchet and need a long range immediately. But overall a knight, archer, or treb seem like way better value when there are no airports on the map. Am I missing some Ballista trick or should the AI value units differently?