Well, you argued with Chekhov's gun when the talk was about Gamma Knife missing Kaido's heart, even though Law said "it should be around here". But somehow Chekhov's gun doesn't work here.
Kaido clearly dodged. Which in turn means that Zoro missed of course. Big Mom screamed at Kaido to dodge so he trusted her. He felt relief after not getting hit by Enma.
Zoro is 2m away from Kaido's huge head at max. Having 2 weeks to train with Enma, with Zoro's attack not draining his arm anymore like in the past. Would be weird if he misses such a huge target from close range.