Update: My mentor glanced at my dovetails and said one word, "gaps"
I was showing him the drawer I just finished for a cherry nightstand, 8 hours of work, and he ran his thumb along the joint and just said "gaps." He grabbed a scrap of poplar, cut a pin in about 90 seconds without any layout lines, and tapped it together tight as a drum. How many of you cut your pins first and size the tails off them instead of the other way around?