Sharp blades are worth the trouble. One, they're cheap if worn out or ruined (especially compared to keeping sod watered and healthy, a problem exacerbated by dull, tearing blades); Two, it also pays to have several so that sharpening isn't an adjunct of gettin' the yard mowed.
I've a 15k s/f lawn at present and if I have to sharpen a blade every week or so it matters little compared to how fast the grass wilts and I have to set the NATIONAL B3 to running it's 180' of hose . . again.
Blade balance matters. Crankshafts deserve it. My lawn equipment lasts ten, twenty years or more so the details add up in the long run (used once/twice weekly, every week, year round)
I've tried files, sanders, Dremel and have settled on a cheap bench grinder as being fastest.
Wipe down the blades (after cleaning) with LC-20/ATF, too.
I've hired a man to do my lawn this season due to my work schedule and blade sharpening was at the top of the list of what I expected under the category of Mowing. I've too much time, effort and energy (and home value) to accept less. Took awhile to find a guy who can actually "see" well when it comes to lawns, a neighbor recommended him. Same with tree trimmers.
Good aesthetic is made up of details, IMO.
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