Tried this at the range today. I found that my arthritic wrists won't allow me to shoot with the gun flat from a #3. Best I could do was a 1.06 on the 3x5. I was matching that speed starting from retention/#2. Oh well, more stuff to practice.
And my bill drills at aprox .25 splits really needed an 8" circle.
I'm changing my recommendation to 1.15 and 8".
Gringop