Shooting five times is normal. Self-defense shootings occur in the tight confines of domestic homes. By the time the intruder enters line of site to whatever room you're in, they will only be a few meters from you. There's no time to fire a warning shot. You also only have one chance to act. Guns don't work like they do in movies. It often takes several shots to disable an attacker. If you shoot once, stop, gauge, and reassess, the intruder will have walked across the room and be on you before you can fire again. You only have a single split-second chance before they can walk across the room and be on top of you. And if they're physically larger and stronger than you, at that point you are at their mercy. And if you only shot them once, now they're angry.
This person acted exactly as they were trained. In self-defense classes, they teach you to not hesitate, to not attempt a disabling or warning shot, and to fire several shots in quick succession. It's the only way to actually use a firearm in close-quarters self defense.
This person acted exactly as they were supposed to. They did exactly as they were taught.