I do it when the rifles new should be stripped when checking headspace from getting chambered anyway.Two issues with Alex Wheelers method:
1) I don't want to punch out the roll pin and remove my ejector everytime I work up a load.
2) Finding your exact "touch" point is irrelevant. It is just one particular datum point to start from. It is no more useful than any other datum point. The precision comes from any subsequent adjustments from that datum point.