Exploding shots use up the same amount of ammo as normal shots. They are less accurate, however, and therefore one could say they are less efficient against fortification (since they will hit the fortification less times). However, against infantry exploding shot is much, much more efficient. It still is, however, more accurate.

I believe that if your enemy is far away from your own troops then it would be better to use exploding shot. If you are close up you should use normal shot.

QUESTION: Are exploding cannon shots more efficient than normal shots in scaring Aztecs?