I don't know it is intentional or not but sometimes wounds won't appear but later they were in bandages (Sengoku after MF war), Kaido after the stab, Luffy after partially hit by thunder bagua etc. But I think Kaido case might be intentional, he might be having peak regeneration abilities....zoans can recover faster afterall...
Also if for Kaido, it's intentional then just defeating him won't be enough, but killing and removing him from the rest of story.