First time I dragged knee (at least without quickly following it up with the rest of my body) was at a kart track on a supermoto 12 years ago.
Now the funny thing is, once you drag knee on a supermoto with a 38" seat height or so, on any other bike the knee seems to make contact pretty quickly. When I built up my 300 race bike, the first lap out on it my thought was damn I'm dragging knee already.
And now these days I'm riding a Z125 Pro at the kart track. Feels like I could put my knees down instead of my feet when I come to a stop on that thing, hahah. Well not quite but you get my point.