Air Defense Blessing usage?

[Chris Coley]

Just wondering If the air defense blessing is used during non air attacks. Several times I've noticed my air defense blessing going away when I haven't been attacked by a plane or Zeppelin. It's my understanding that it only affects Air Defenses and not towers..or am I wrong?

 

[Wicked Odie]

Does the blessing itself say per 1 defense? If that's the case then if you're attacked once, no matter if it's 1 troop or 1 plane or whatever, it will go away.

I fully believe that all blessing should be timed and not per use.