Of interest you can audition the hone with the razor.
He can mark the spine and the edge with a black magic marker and
give it one or two gentle smooth strokes. If the entire edge is touched
by the hone and the same is true of the spine then the razor and
hone "Play together" and lapping is not necessary. Some
tuning is possible by adjusting the stroke on the hone so remarking
and retesting may be a valuable exercise.