They were very lax with it. Part of that was the rigid German system, part of that was the thought that no one could crack the code. We know perfectly well how the Enigma operates (today, that is) - I find it hard to believe there's a message that's still unencoded unless it was a joke or a faulty encode where the writer added some salt to the message. The Enigma itself wasn't unclassified until 1977 (I think) in the States, so perhaps there's something in that message that's damning? I think the German overconfidence in their superiority probably did them more damage than anything else. The British were turning out aircraft be dozen from piano factories and tunnels. The Americans were just fucking nuts. The Russians stood back and let Mother Nature do them in. So many mistakes were made because of underestimating that it eventually lost them the war.