In my opinion, based on scientific research (reply #21), the more plastic washer on the 3PDT, the longer the footswitch will last. Aren't they some sort of 3PDT Fountain of Youth ?
Thanks to the plastic washer's very interesting properties, more vibrations will be dampen, and they will also absorb the shocks more efficiently.
In fact, i think two white washers is a minimum if you really respect your circuits and your own work... that's definitly a sign that a pedal builder cares about his builds.
No offense to the back-stabbing plastic-washerophobics, but they do need to step up their game, and evolve past their rejection tendencies, in my humble opinion (based on scientific evidence).
Once, several plastic washers have been stolen from my stash. I had to use my credit card to build my own plastic washers. Couldn't eat and live as usual for weeks after that. Lost several pounds, i also got ill, but it was well worth it.