I have been the proud owner of a 240mm Kikuichi TKC gyuto for almost 2 years now. It has seen heavy use in professional kitchens, but has never been mistreated or used inappropriately. When I first received it, I would touch up on stones weekly and give a good sharpen on a monthly basis (50/50 edge), 600/1000/4000/6000 stones, honing on fine ceramic frequently. Now I don't consider myself god's gift to knife sharpening, but I know what I'm doing. This knife has been an excellent workhorse and given me no reason to complain until recently. I'm starting to notice the edge retention decrease to the point where I'm sharpening every 2-3 days. I'm also having trouble getting it hair-popping sharp.
My theory is that the knife is getting worn down to the point where it needs to be thinned. It doesn't really appear that way; the profile hasn't changed noticeably since I have received it, this is just my educated guess. Any other theories would be appreciated. In the case that it does need to be thinned, I am hoping for someone familiar with the process to walk me through it. Is this something that will need to be done with all knives eventually? It seems I saw a video tutorial a year or two ago but I can't seem to find any now...Thanks in advance.