Ever notice how the same people continue to comment on other's posts without offering anything positive?
Yes, that happens as well as those complaining of nothing positive. Conversation and understanding.
So consider, my interpretation of four conditions of a bolt a holding a plate down, first only a bolt, holds tight, but under vibration may loosen. Next a flat washer, and bolt holds the same, but with perhaps a more uniform tension, but also will loosen with some vibrations. Next a flat washer, split lock washer and bolt, this will hold better to the plate, but can still loosen under some circumstances. And lastly the split lock washer and bolt, this holds best as the lock washer grips both the plate and bolt from turning loose.
The suggestion of the use of an o-ring is similar to the lock washer and bolt.
With a positive addition, as the grip screw is tightened the o-ring will squash out, expand, and better secure the grip while gripping the bushing and screw underside, with minimum stacking.
Adding a washer may extend o-ring life, but the washers cost four times as much, and reduce the locking feature of the o-ring gripping the top of the bushing, and add to the stack.
I only use square bottom pin cover grip panels so must remove them every time I'm doing much. The o-rings do get chafed after a number of ass/dis-assembles, but at the price is hardly a concern, I mean 25 full sets, (100) for 6$. I have used these for quite a while now and still have plenty of the first package of 100. They should be considered a consumable, just as any damaged split lock washers should be replaced.