A good flat mill file and give her five full strokes per sharpening for softwoods, 2-3 for hardwood. That will keep your rakers about right. Typically a good pronounced flat spot on the rakers, properly angled, and you're pretty much good for the life of the chain.
Folks get waaaaaay to uppity about their chains. The trick is to get a good edge established, clear the gullet, and keep the corner at a wicked point. Keep well away from rocks and metal and dirty wood and you won't spend much time playing with a file at all. Inspect your chain regularly, and just keep that hook mean.
These foothill oaks are very forgiving compared to the nasty high-desert trees I grew up with. I think I've filed the 32in chain on my 500i maybe 5 times in the last year, usually because I kissed a rock bucking something big.
Let's see, five species of oak, three of pine, and Western Red Cedar, manzanita of various species, buckeye, willow, sycamore, various brush species including buckthorn and mountain mahogany, redbud, dogwood and various fruit trees, so lots of variety on that chain. Just sayin. It's also eaten som granite and t post...just sayin...
