I would presume that it's the same as other round in that regard, with 1 shot to the head or 1 shot to the big toe being more or less equally effective.
Based on what I've read, it seems like all the number of shots indicates is how many times the shooter missed the vitals before he finally landed a critical hit.
You are on the right track, but not there yet. Yes, you can scramble a person's brain with a long needle, or shoot it with a .177 pellet air rifle or .50 BMG. So, would you consider these to be equally lethal? The needle probably won't take of your big toe, and the .177 pellet probably won't either, but the .50 BMG could take that sucker right off. They are not equally effective. You might survive getting poked with a needle in the brain. You might survive a .177 pellet to the brain as well. I would not give you very good odds on surviving a .50 BMG to the brain.
The number of shots may or may not have to do with missing the vitals, but also in the ability of the shots to reach the vitals. Larger and more powerful calibers have the potential to create larger and more damaging wound channels than smaller and weaker calibers. The larger the size of the wound channel, the more likely it is to involve more of those vital you mentioned. With the advancement of medical science, in many cases people dying of wounds 20 years ago are surviving them today, but people were surviving wound 20 years ago that people weren't surviving 40 years ago, despite being shot in their vitals.
Here is a neat study on the lethality by caliber groups that appeared in JAMA based on criminal assaults.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2688536
This was one of their findings...
The results here support the view that the intrinsic power and lethality of the weapon had a direct effect on the likelihood that a victim of a criminal shooting died.
And the group of guns that did best in surviving? Those shot with the less powerful calibers such as .22lr, .25, and .32. (called small caliber in the study).
Here is a nifty study on .22 shots to the brain. A surprising number survived. Reaching the brain and penetrating into it isn't necessarily enough for death.
https://pubmed.ncbi.nlm.nih.gov/3311325/
So in the real world, caliber size/power and effectiveness do have some correlation and as indicated, the greater the disparity in caliber size/power then the greater the disparity in terminal efficiency.