Bullseye discipline shooting and defensive shooting are very different with regards to the dynamics involved (obviously), but also in what is referred to as acceptable accuracy. As Mike mentions in the video, putting holes in a small group on paper targets for a score is a lot different than putting effective rounds into a bad guy to stop a threat. This video provides a pretty good discussion of the difference between bullseye accuracy and defensive (combat) accuracy. The idea is to stop the threat. More hits to an acceptable level of accuracy within an acceptable are (i.e. "center mass") creates more likelihood of incapacitating a threat.
I have worked with defensive shooting instructors who espouse the "other" theory of defensive shooting, that of putting all defensive shots into nearly the same place. The idea of that philosophy is to create a larger wound cavity in a single place, and a single vital organ. And then there are others who believe that shooting at a faster cadence, placing more rounds on the target with the highest delivery speed that will allow for accuracy, will be more effective in stopping a threat. In other words: Putting all shots into as close to a single hole as possible, versus spreading more shots out over a critical area.
But I personally adhere to and teach the philosophy of combat accuracy with a greater shooting cadence versus the idea of trying to put defensive shots all in the same hole. Getting a lot of shots off faster, but still having the marksmanship to put them all in the acceptable accuracy zones (in my humble opinion) will increase the likelihood of putting rounds into vital areas and stop the threat.
Whichever you decide to use, remember to practice, practice practice. Practice both and see which one works for you. Remember: In a crisis situation, you will never rise to super-star performance. You will always fall back to your level of training.