Riveting question

I'm spending a drizzly day going thru the section of AC43 dealing with
riveting and have an initial question. I think I know the answer but
could use some comformation.

Figure 4-5 shows Rivet spacing for single-lap sheet splice. It shows a
double row of rivets in one case and the note "Strength thru this
section is 75% of sheet w/o holes". In the second illustration it show
more than two rows of rivets and a greater overlap with the note
"Strength thru this section is 83% of sheet without holes".

My question is/was "How do you determine how much overlap there should
be?"

My tentative answer is "The more rivets, the stronger the joint. If
75% of the original sheet strength is fine, then overlap enough to
sustain a double row of rivets. If 83% is needed, then go to an
overlap that will support three rows of rivets. "

Is my logic correct?

Also, is 83% as good as it gets? if so, why show more than 3 rows?

- Mike