Armoring WWII Bombers

An anecdote goes as follows:

"The Germans shot down too many Allied bombers during the World War II, so the British sent for an American expert. The expert went to Great Britain to take a look at the damaged planes which had made it back. After considering the situation, the expert had extra armor installed to undamaged places of the planes."

Was the expert right, wrong, both, or none?

Yes, he was!

One could say that the expert was right: planes had made it back so any damage in them was apparently non-lethal, thus the existing damaged places did not need extra armor. To improve armor on non-lethal damage would be wasteful, as such armor would not be needed. Obviously those planes which did not make it back had received hits on the places where the examined planes had no damage, thus armoring the untouched places would help to increase survivability.

On the other hand, one can argue that the expert was wrong: if there is a limited amount of damage the planes can take before suffering problems during a mission, the places where the planes got hit the most should be protected. Therefore, by armoring the places where no hits had been received, the expert did not increase the protection available to the crew, but only succeeded in increasing the weight of the airplanes thus making the situation worse. Thus the expert should have armored those places which got hit.

There would also have been a third option, which would have been to do nothing. This would likely have been a worse course of action than either of the previously described ones, as doing nothing would have only upheld the status quo and not have made things better for the crew of the bombers. If the expert was very unsure about where to add the armor, this would have been the best course of action to take.

Thanks to Scr for pointing out the anecdote.