My two cents on this.
That ritual circle symbol from the examples shown look 'complete' as there is no breaks in the circle. So depending how long that old ritual circle was there, part of it could of been washed away or distorted by the natural elements which I am sure making that circle unusable which is also I point out why it was done in fresh blood so that ritual circle symbol could be 'complete'
Although this is all speculation on my part from observing the examples
The circle I am using is indoors and has been completely undisturbed.
I'm not completely dense, I am aware Kamui is just trying to get me to rage so he can ban me. It's not gonna work though. I have a complete circle of old blood, could the blood be chipped to break the circle? Sure, but it wasn't. It's not like anyone tried to sabotage it.
Ok though, not race, you have to have your hair slicked back like Hidan to do the jutsu.
Again, to recap, My Circle: Complete, unbroken, circle of dried blood due to it been contained in an undisturbed chamber.
Hazama is also correct, if Kamui were to win this I would just have to repost and I'd make a circle by unsealing more of his blood.
Of course Hidan has to draw a circle each time, because, what else would he do? Pull an old circle out of his pocket and slap it down on the ground?
Kamui is using completely circumstantial evidence. "There's a murdered person in this house. I saw Steve go into that house. Steve must be the murder." No, that doesn't prove anything.
"Hidan draws a circle with his blood each time he does the jutsu, there for it must be a circle of fresh blood to work." Again, no, there is nothing to suggest it has to be a fresh circle. How else does one create a circle of blood if not by spilling blood on the ground? That's literally the only option you have to create one so of course that is what he does.