Kaido recovered and seemed to have stopped the bleeding instantly.
Not so much from the internal damage caused by all of Luffy's attacks, which is starting to show pronounced effect, but that is to be expected, Zoro only landed 2 semi effective blows, whereas Luffy has landed many, including far more effective blows utilizing adv CoC, which Zoro doesn't have access to.
It's funny that Oden, someone who was one shot by base Kaido, created 2 giant scars in a 1vs1 setting, wheras Zoro creates a thin tiny scar that Oda hasn't bothered to draw since 1010, while ambushing a neck turned Kaido focused on Luffy, who didn't realise Luffy's subordinate had base CoC