I don't practice with my stone points. Instead, I insert a thick, blunt foreshaft into the front of my cane arrows and just practice with that. If the arrow flies straight, then I make another foreshaft and mount the stone point onto that one...being sure that it weighs the same as the blunt foreshaft. That way I'm guaranteed perfect flight.
I don't practice with my stone points because I've never had any problems with wind planing. Stone points don't have the flat surfaces like metal points that catch wind and steer the arrow. Instead, they are much rounder in cross section so air tends to roll over them.....it's those flat surfaces of the metal points that cause arrows to fly erratically. Some of you might have different experiences, but mine has shown me that stone points fly much better than metal ones.