I remember these. Big M did it in 1 or 2 races a weekend for about a month. Then dumped it never to reappear.
Not sure who suggested but would guess it was just try at something different.
I didn't care for it after it started- screwed up playing horizontal races.And how do you handicap harness turf. No Tomlinson #s

. I believe I used horses that had good form or liked the slop. Didn't work for me.