Understand that a lot depends on individual eye sight, but is there a preferred target size/shape/dia for regulating a DR using express open sights at 50-60yds?

Weather finally looks to be decent this weekend and I'm planning to get my 'questionable' 450/400 NE 3" SxS shotgun conversion out and see where/how it shoots.

I like a 5.5 inch round shoot n c black target. The front sight usually shows a fine edge around it at 50 yards. I also cut this target into quarters and have point facing up and I put one of the 1 inch round dots on top of the point. This gives a little more of the aim small miss small effect.

I like the 12" Shoot and See targets at 50 yds. It gives that nice concentric circle around the front bead. And no, I don't need the 12" targets for my eyesight. Even at 54 I still correct to better than 20/15.