This thread has become very informative. I do appreciate everyone's comments.
James: Your comments make a lot of sense, though the strength and durability of the large number of spi, do to so many perforations in the leather, is rather counter intuitive, from my unlearned perspective. In reviewing TC Albert's very informative book, last evening, I did see, finally, where reference was made of two original bags constructed with 11spi, which supports what you reported.
An #8 overstitch wheel was bought a few weeks ago, and I have been contemplating buying #10 and #12 pricking wheels, which led to my apparent confusion as to the durability of relatively high stitch counts, in leather goods.
I also viewed your web page, and I must say your work is exquisitely executed. Very, very nice. I may steal...ahem...borrow...some of your ideas, regarding construction and embellishment, though not so eloquently executed, for my own work.
I have done quite a lot of research, into several areas of 18th century life ways, however, my research into period leather working is practically nil.
That will be rectified. What little research, recently done, suggests the D shaped harness buckles were probably more commonly used in the 18th and early 19th centuries to secure strapping, of all kinds, than the square buckles, and especially the round buckles, with a center bar, so often used today. There is much to learn.
Again, I want to thank everyone for their comments. I do appreciate the help.