I suspect the grip and disc orientation in the hand matters. So the knuckle on the index finger ends up either in the way or out of the way.
I have my finger pads on the inside rim rather than the flight plate and I sit/leverage the wing right against/inside the index knuckle. If I moved the disc deeper back into the thumb webbing/joint then the disc would have to drag over top the knuckle slowing down the pivot and adding wobble. It also feels very uncomfortable jamming the disc as far back into the thumb joint as possible.
If I reorient the disc and put my finger pads on the flight plate I can feel how my index knuckle is not in the way nearly as much and the edge of the sits more inside the index palm side rather than the top side/knuckle of the index.
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