Patrol or attack -- planes vs AA guns

I have a large stack of planes attacking a large stack of mixed units with 4 AA guns that do 5 damage to planes. If I patrol, does he defend everytime I attack 4x per hour for 25% damage. So that in one hour I do my full allotment of damage but he does 4x his 100% or 20 X4 = 80 points of dameage to my planes plus all his other units.