When in academy and afterwards we were taught double tap then one to the head called a Mozambique Drill...but when I went to a specialist training program we were trained to fire center mass until the target was down. I liked that drill as it required less accuracy and was much quicker. Of course that drill was more about fire power and target suppression but even on the street I would think it would be much more effective. One of the instructors could empty a Glock 19 (15 rounds) almost instantly (sounded like a machine gun almost) and would drop and reload on the move. It was very impressive and yet required less skill than the Mozambique Drill. As for self defense...same deal unless engaging multiple attackers.