I don't necessarily disagree with your argument entirely but this is wrong. Zoro's been fighting since chapter 980. Ofcourse he is fatigued.
The mink medicine was stated to heal his injuries. It doesn't take his fatigue away. It's like playing a sport for an hour and injuring your ankle. The medicine will heal your ankle but won't take the tiredness of playing an hour away.
The mink medicine was stated to heal his injuries. It doesn't take his fatigue away. It's like playing a sport for an hour and injuring your ankle. The medicine will heal your ankle but won't take the tiredness of playing an hour away.
Katakuri could fight several hours using Advanced Haki plus Awakening, that should be taxing af.