What I was after is seeing where the gain in DoF is overwhelmed by diffraction. We hear and see a lot about it, but the real world exist in my head, so here we are.
The first series shown in post #1 was shot with the focus set to the minimum which extends the the lens and increases the focal length. The increase in focal length is what allows the smaller f/stops beyond f/22.
DoF increase with each progressively smaller f/stop in each image, so the greatest DoF is in #6. Diffraction is also increasing with each progressively smaller f/stop in each image.
The sharpest fibers in #1 appear progressively sharper in #2 and #3, level off in #4 and softens slightly in #5. There is a trade-off between #4 and #5. #4 is slightly sharper at the focal plane than #5, but #5 has slightly larger DoF and there are fibers in #5 that are sharper than in #4 due to this.
Step back to the reality of a normal print size and there is not much to distinguish 4 & 5 due to the aforementioned trade-off and #6 doesn't look bad at all.
#6
The second series shown in post #3 was shot at less magnification and it shows that diffraction occurs at a larger aperture than it does when the lens is focused at 1:1.