I have always believed that the most important shot fired was the first one. Regardless if it was from the good guy or the bad guy. The bad guy will almost always have the advantage. He is prepared, and will use the element of surprise. In order to win, you must shoot first, be fast, be quick or be dead as they say. In training I will focus on this belief. Yea, you might be lucky and get off a second shot but beyond that you are pressing you luck.
Focus on the first shot fired, not the last shots of a 10 Plus round firearm.