I heard someone giving the advice a long time ago to take new leather-soled shoes and walk them a few hours on a concrete path strewn with a reasonable layer of sand so that the grains of silica etc become embedded in the surface. Not easy to do perhaps, but have you any views on this ?
I don't. Seems somewhat counter-intuitive, doesn't it? Except that in this day and age that's most likely what we do even if we aren't really trying. Many urban surfaces we walk on are comprised of grit that sooner or later becomes sand-like.
To take that to its logical extreme...when I was doing shoe repair, I saw many work boots with crepe soles. They'd pick up sand and even small, sharp pebbles pretty easy...sometimes the grit would be embedded so deep in the rubber that you couldn't know it was there until your recently sharpened knife hit it. But it didn't stop the rubber from wearing out...and pretty fast.