Wow, those look like really great shape plugs for a quart of oil every 200 miles. All my old oil burners looked much worse. Your #1 looks off on color, maybe there's something there. I've been told compression is most important to be wearing evenly across the cylinders and that #6 is usually the worst. From that your #3 looks "not like the others". But your performance is great.
For reference, mine measured 100-110 compression.
I don't think your rings are leaking the oil. It's gotta be going somewhere else. Rear main seal or somehow directly into the exhaust manifold? Where else could it be going?
Oh yeah, I hate never-seize that I see you put on your plugs. We used to put that on the handles of peoples tools in the canning factory for laughs. Nasty stuff, but it does work even in salt-water environments.
