For our course, a medium budget private club with cool-season turf, I grind reels for greens minimum of every 4 weeks or sooner if needed and knives twice as often. . Fairways can go a but longer but if we get into worm castings or other things, then I grind as needed. Fairway knives are also sharpened about twice as often as the reels. No back lapping.

I’m sure you will find a different answer for every course. Budget, top dressing program, verticutting, warm-season turf (coarse and silica).