Warning: my old shop mentor laughed at my sliding dovetail jig and he was dead wrong
Back when I was a helper in a cabinet shop near Sacramento, my old mentor Rick watched me set up a sliding dovetail jig on a bookshelf job and just shook his head. He said hand cut dovetails on case work are always faster because "the setup eats you alive." I believed him for about 2 months and hand cut every joint like a chump, and my forearms hated me for it. Then one Friday I had 6 shelf boxes due and figured what the heck, I'd time both ways on scrap. The jig cut a clean joint in 4 minutes flat and my hand cut took 22, and that wasn't even close to my worst one. Rick still swears the jig is a gimmick to this day, which cracks me up every time he visits the shop. Funny part is he taught me everything else I know and he was spot on about most of it, just not this. So what's the one piece of shop wisdom you got handed that totally fell apart once you timed it yourself?