IMO it is much easier to do if you make one long stroke from heel to toe. This way you will feel if the whole blade feels the same. If you test in a lot of spots, than the pressure can vary, the nail spot too, and it is much harder to compare 4-5-6 short feelings to a long one. Sometimes there is only a very little spot in the edge where it doesn't feel right, and you can miss that if you test only portions of the edge.