Perhaps, using a longer radius is a bit more stable with a larger radius like 12' or 13' when using a shallow hollow like 3/4"? I have seen people claim Gretzky used a 1/2" but only a 7' radius. Paul Coffey used an 1" or higher, but I have no idea what his radius was. The correlation between the hollow used and the radius must be fairly significant. Mentioning only one of the two aspects seems to be leaving a lot out of the equation.