Hi, aplant.
While the speed bag isn't the end all, be all, I do find it useful. I just don't see why doing it "the boxing way" confers more benefits than working the bag the way you would fight. If it's a question of keeping your hands high, fine. But why not in a proper guard, instead of with your elbows almost to your shoulders and your body uncovered?
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Just when you think something is foolproof, they come out with a new and improved type of fool.