I thinned 3 acres thus far this summer, and I hope to thin 2 more. We're working on the north line of our property, which is along a ridgetop.
On the other side of the ridge is an unmanaged, overstocked Douglas Fir stand on a steep slope. If a fire approached from that direction, it would move swiftly onto our property. We would want such a fire to slow and drop to the ground, rather than rushing through the canopy toward our cabin. The ridge can be a line of defense.
Our strategy is to go for some extra spacing in the trees right along the line, creating a "shaded fuel break" about 40 or 50 feet wide for the full width of our property. Then over the course of 200 feet the trees "feather in" to a more dense spacing, reaching the standard 20 foot stem spacing.
Along with that strategy is an overall preference for Ponderosa Pine, which is more fire tolerant than Douglas Fir, and has a better chance of surviving a ground fire.
I'm an amateur at felling trees, and always will be. Thinning on a moderate slope seems to take me about 20-25 hours per acre. That's including time for hung trees, teepees, bound saws, thrown chains, sharpening, and bushwhacking around the hillside from tree to tree. I try to get started early and get in at least 6 hours a day. I can fell anywhere from 10 to 25 trees in that time.