I bow to your knowledge and experience, but styli do wear, albeit after a longer time for Koetsu. One thing which has puzzled me with Ks, Dimitry, is bias. Ks need much less than other cart's (don't ask me why, but it's well-known) and if on a 12" arm (like mine), virtually none at all. However, many K owners have found their cantilevers slewed a bit after, say, 500 or more hours. Mine is slightly so (to the left looking from the front, or toward the inner grooves).
Many have reported no adverse sonics, but I'm sceptical, as the stylus MUST be tracking the groove at a slightly offset angle. Can I assume, then, that if one can ascertain whether it's been too much or too little bias which has caused this, reversing this for a hundred or more hours would bring the canti. back to the straight and narrow ?
I shall be re-mounting my K sometime this coming winter and although I could possibly compensate in set-up, would prefer not to for obv. reasons. This subject has been bothering me since I first noticed a very slight skew a few years ago.