IF half of shootings involved one shot and the other half involved 5 (just throwing out numbers), the average would be three. However, somone carrying 3 rounds would only be prepared for 50% of shootings. Now, that example is FAR too simple, but I think the point is clear. Judging by averages is not always wise. I do not know the data on how shootings are distributed. It could be that the VAST majority involve less than 3 rounds, but some shootings involve a high number of shots. It could be that a large percentage involve a larger number, but others only involve 1 shot. I do not know. Does anyone have that information?
Statistically, none of us is likely to need a firearm on any given day; yet so many people still carry one. Statistical outliers are what we are all trying to deal with.
I would carry whatever I felt prepared with, judging by the potential situations around me. I would probably carry more in a dangerous area than in a relatively safer area. It all comes down to the compromises we are willing to make, otherwise we would all be living in bomb shelters!