I think a skid shoe on a rotary cutter is different than what's on a blade or rake. The front shoulders of the housing of the rotary cutter -- the lower edges of the enclosure on the front corners-- get a lot of wear because users drag the cutters thru uneven ground and over rocks, stumps, etc. These corners have wide, thick metal welded on the bottom -- they're what's called skid shoes on cutters. If you wear them out, you're really working hard on rough terrain.
jim