Feathed, how are you verifying pivot to spindle distance?
One can adjust a cartridge to one or two null points all of their life and never get anything close to correct if the pivot to spindle distance is not dead on. This is what an arc protractor designed for a specific p2s provides the user. None of this getting "close enough". It is possible to get it dead on at a point past the spindle and at a point off the edge of the platter. That is how you know it is tracing the proper arc in the proper location. You can't do that with any other type of protractor. If you get p2s correct, aligning to the null points HAS to be more accurate regardless of which alignment style you use.
One can adjust a cartridge to one or two null points all of their life and never get anything close to correct if the pivot to spindle distance is not dead on. This is what an arc protractor designed for a specific p2s provides the user. None of this getting "close enough". It is possible to get it dead on at a point past the spindle and at a point off the edge of the platter. That is how you know it is tracing the proper arc in the proper location. You can't do that with any other type of protractor. If you get p2s correct, aligning to the null points HAS to be more accurate regardless of which alignment style you use.