I wish this was set up like Quora or something where we could comment under individual reply's. This relates to someone's comments, but emphasizes that the way this game is set up is for retired people, unemployed, and frivolous spenders. When I have the time, I use the multiple air groups and reset their patrol area before the 15 min timer goes up and they attack. That way I can destroy a larger stack using 100% efficiency only defending, while they are whittled down like flies to honey. What student of the game would not use that mechanic to their advantage?