You see, when the MC is defeated, it is supposed to be an absolute low. So when he gets up with a power up, you would normally expect him to win the fight. This is just basic story telling.
But Oda, having already made kaido far too powerful and Luffy far too weak, spammed this 3 times, thereby making Luffy's losses and power ups have virtually zero impact.
Ultimately this is just shitty writing on Oda's part. After already losing to kaido in act 1, Luffy should not have lost more than 1, maybe 2 times on the roof. 3 was just overboard.