I actually had 3mm of washers on my left pedal at one point, I am down to 2mm, and considering going to one. My fit and fitness has change quite a bit since I first started using the washers.

I started out with matching my stance on the bike to what I did when walking (toes pointed slightly outward on both). Currently I still maintain that on my left knee, but my right seems to want to actually go with straight or slightly pointed inward, and so I've rotated the cleat to match where the foot seems to go. I just pay attention to where my feet want to go, and let them I ride a triple, so my q-factor will always be wide, as I need those low low gears for spinning up hills. If I don't spin, my patellar tendon in the right knee is very mad at me, so a triple it is. I am going to try to move the cleat inward a bit as I've noticed that my knee wants to go inward a bit.

For me, I just follow what my body tells me and adjust my equipment accordingly. Having a fitter who gets your problem, and a PT who specializes in working with athletes also helps.