Tom, I think that you misunderstood me. I am not talking about leaf shutters in general. I am talking about the particular leaf shutter that came with the Super Speed Graphic.
I have never used one. I have never checked the speed of one with my Calumet shutter speed tester. All I did was ask a question about it on Large Format Photography Forum.
What I learned from people I trust was that this particular shutter is unreliable and expensive to repair. It was just a bad design from the beginning and never as fast as claimed.