I was putting my title blocks in the wrong spot for years

I was working on a set of shop drawings for a steel fabricator in Chicago and the checker kept sending them back. He finally called me and said, 'Your title block is in the wrong corner for our nesting software, it's adding an hour to our prep time.' I had been placing it in the lower right on every sheet for three years because that's what I was taught. Turns out their plasma table software reads from the upper left. I had to go back and move it on 40 sheets. What's the most annoying standard you've had to relearn for a specific client?