When we were first introduced to Hidan we were not privy to see his fighting but rather his after battle ritual were he laid in his bloody circle and triangle. This particular ritual/ceremony annoys Kakuza because of its long length. I believe this ritual is used to heal Hidan's body since Hidan wrecks his body presumably everytime he uses the Curse ritual soaking up damage on purpose. Hidan in his circle Hidan does not have a single scar on his body except for the long spike he leaves in his sternum . Nor does he have any kind of wound after the Nii Yugito(2 tails) and Chiroko fight. He must have had lots of tough battles including the one where he got into the Akatsuki yet his body shows no sign of any damage. Hidan took an insane amount of damage with his fight with Asuma and company. I do not know the significance of leaving his long spike in his body while he rests and heals. It must be part of his religious beliefs, Jashin.