But it becomes irrelevant when Luffy uses a mode that requires high stamina while holding back on his most powerful asset (ACoC with internal destruction). He was fighting Kaido for hours using ACoC prior to G5, while using G4 and Gear stacking. After that, he used all types of advanced Hakis in G5. Against Kizaru, Luffy was goofing around most of the time, until he used ACoC in that one last punch.