Seems most around my way don't sharpen the blades on their rotary cutters, but then again they don't use them on lawns. The guy I most often cut stuff with, a hunting club buddy, hasn't sharpened his since buying the unit used a decade ago. Whatever.....I sharpen blades the "quick and easy" way, i.e., laying on my back under the cutter (with safety wedges) with an angle grinder, once or twice a year depending on cutter use and what I've inadvertently hit with it. I used to take off the blades and fine tune them on a grinder (modestly sharp edge - like when new) once a year when I was clearing saplings and heavy brush, but now every 2 years as it's now mostly weeds and light brush, and every few years I'd buy new blades. Yup, with a tractor 15 HP lower than my friend's I could cut everything he could re. saplings, and when I trimmed the weed-filled edges of roads the stuff didn't look totally mangled behind my cutter's sharper blades. Now, as to balancing it's a challenge given the blades weigh ~ 23 lbs each (Woods 72 behind K L3400), and one has to get the blades within an ounce or so if one doesn't want major vibration and cutter spindle stress. Couldn't use my kitchen scale with its' 15 lb limit, so went the route of Solomon - an 8' bar (straight 2X4' in my case) with hooks at each and a U-bolt at its' midpoint - would suspend bar from garage hoist, place a blade on each end and then just watch how it balanced out.
So, big tractor and only brush/saplings - sharp blades not critical.....for smaller tractors or fine weeds and grass, then it's quite useful.
So, big tractor and only brush/saplings - sharp blades not critical.....for smaller tractors or fine weeds and grass, then it's quite useful.