On some 'scopes, I can feel the adjustment range squeezing a bit tight at the end of its travel and with no exact hard stop to count from, so I don't trust half the total number of clicks to be exactly symmetrical on either side of optical neutral (on-axis), and on a few scopes the difference is substantial. I also have one old scope that doesn't have clicks; just continuous adjustment. The spinning method is accurate for both situations, but I've never actually used the mirror method—only read about it—so I don't know how it compares to spinning for resolution.