Jeff said it quite well... You never meet someone who deployed a firearm in a defensive situation that wished they had fewer rounds than what they had. Or say extra training wasn't worth it.
I went to the store today. I had 49 rounds, 6 magazines, and 2 pistols. (I was carrying light) When I go to a range, I shoot 10-17 rounds of defense ammo from each pistol I carry. They are in defensive drills, not plinking. Why? Because the shoot differently, ballistics and recoil. There are no do-overs for defensive situations. My daughters, wife, and I have one shot at life.
A range trip costs me about $100 in ammo a month. Life insurance may take care of my family, but it doesn't touch the void left behind. I decided safety is paramount and live accordingly. So take some time to consider why you carry. Think about the OP and what can happen when "I'll only be out for a few minutes."