Other countries have been more careful. For example Hitler specifically forbade the use of Röchling shells without his express permission because he was afraid of the other side copying them. The Allies were also nervous about the over-liberal use of VT fuses in case the Germans copied them because it would have made their air defences vastly more effective, but by that point in the war there wasn't much risk of that happening.
What a great way to defang them long term.
Other countries have been more careful. For example Hitler specifically forbade the use of Röchling shells without his express permission because he was afraid of the other side copying them. The Allies were also nervous about the over-liberal use of VT fuses in case the Germans copied them because it would have made their air defences vastly more effective, but by that point in the war there wasn't much risk of that happening.