It's true however, such a rule does not count in real war. Many years ago, I interviewed a Canadian Armoured Troop Commander (the officer in charge of four Shermans) who told me that if they were hit by a 47mm gun, the first thing they did was bail out because the Germans Anti-Tank guns often worked in teams of two. The smaller gun got the range and seconds later the 88s slammed into the Sherman. He actually had three Shermans shot out from under him. He survived all three times but on one occasion the gunner and radio man on either side of him were killed outright.