Suzuki's vague about the alternate thicknesses. I assumed it was to adjust the stack height for accumulated manufacturing tolerances and/or wear.
I've been snooping around and noticed an error in the clutch parts fiche. If you look
here, you'll see parts 21, 23, and 24 are the hub nut, hub washer, and hub wave washer. The picture has the hub washer located between the nut and the wave washer. The order should actually have the wave washer in the middle. It's been this way for eighteen years now and traces back to the original release from Japan. They got it right in K7. I also see pics of the 09160-25073 driven gear thrust washer and the 09160-25077 hub washer as blue, indicating that they're hardened. But the 09160-25056 hub thrust washer (22 in the fiche) is not. Go figure.