Torpedo reliability as a testing lesson

Why were some Second World War torpedoes more consistent than others, and what would a British-Japanese Long Lance-style development path imply?

The navies that practiced and tested torpedoes most found faults earlier, while reduced U.S. test budgets produced wartime failures; a continuing British-Japanese alliance could also encourage joint development of larger torpedoes.

Torpedo reliability followed prewar testing and practice more closely than national reputation. The Royal Navy, Japanese Navy, Italian Navy, and Dutch Navy all invested heavily in learning whether their weapons worked, while Germany corrected early failures quickly. Reduced U.S. testing budgets left serious faults to be discovered in wartime. Destroying expensive hardware during trials was still cheaper than losing ships and crews to defective weapons. If the British-Japanese alliance had endured, both navies' interest in larger torpedoes could also have encouraged joint development.