I believe that riders of high performance bikes including racers avoid lock washers for the reasons already stated, including the clutch nut. They are soft and they take a hammering likely to slightly loosen the pressure on the shims. It is likely that a soft lock washer could reduce the pressure on the shims from 65 ft-lbs to zero so goodbye shims. I use a cheap impact driver drill to belt it up to about 80 ft-lbs ( the capacity of my cheap driver) with some loctite on the thread.
Similar to me Col, belt it up with Loctite. Just as a related aside, when I put the driveshafts on the Octy, I used the old, felt type gaskets. When all the bolts came loose, it turned out that the gaskets had disintegrated. My theory is that the failing gaskets created a tiny gap that allowed for movement in the bolts, which then loosened completely to failure over 6k miles (no Loctite). This time, no gaskets, a damn good degrease, a good dollop of Loctite, and torqued to slightly above spec. After marking them up with permanent marker, I've checked them over 2k miles and no movement has taken place.
For the clutch centre nut, that was the same as the cush except for the fact I did include a tab washer.