The 90 year old meat counter at a place in Cleveland changed how I trim

I was up in Cleveland two weeks ago visiting my wife's folks and we stopped at a little old butcher shop on the west side that's been running since the 1930s. The guy behind the counter was maybe 70 and I watched him break down a whole lamb shoulder without a single wasted stroke, and his trim pile was so small it fit in one hand. He told me his dad taught him to follow the seam with the tip of the blade instead of sawing through the muscle, and I tried it at my own shop when I got home. I lost maybe half a pound less per shoulder that first week, which adds up fast. Has anyone else picked up a trick just from standing there watching an old timer work?