Because luffy’s training with Rayleigh was specifically about haki. Rayleigh was specifically focused on improving luffy’s haki
Mihawk was specifically training zoro to improve his swordsmanship
Same way Sanji needed haki to become a stronger fighter but it still wasn’t the focus. Like yeah he learned about haki and even what conquerors was but it still wasn’t the main focus. He was pretty much training his body and improving his black leg style
I don’t understand what you are getting at in this thread
Mihawk’s training to Zoro as far as the story implies is simply mihawk telling Zoro that he needs to unlock CoA… that’s it… Everything else Zoro improved in we are not told has anything to do with mihawk… And that makes sense since Zoro has been demonstrated as the only strawhat that actually trains on his own regularly already
so if Zoro landed with Rayleigh or Ivankov the only difference would be whether Rayleigh or Ivankov told Zoro that he needs to unlock CoA… That’s all… And I assume Rayleigh knows that Zoro should unlock CoA since Rayleigh is a swordsman and Ivankov probably knows since he’s a veteran fighter who at least has come across a swordsman
as far as the story has implied, the only way Zoro is any different is entirely based on whether whoever is training him TELLS HIM COA EXISTS… That’s all… Mihawk didnt even tell Zoro how CoA works… He just told him it exists and he needs it and then Zoro went off and did it by himself
For Luffy it was WAY MORE hands on with daily direct training for Rayleigh so Luffy would lose out the most from getting sent to Mihawk or Ivankov. Mihawk would at best just tell Luffy to go train himself like how he told Zoro, and Ivankov would help Luffy more but since Ivankov doesn’t have CoC he would not help Luffy learn how to use CoC so Luffy would still end up weaker… Also the lack of the giant animals would mean Luffy wouldn’t unlock G4
Sanji is closer to Zoro in that he basically trained himself. But the difference is that Sanji isn’t like Zoro who regularly trains himself… Sanji ended up training himself because HE WAS FORCED TO under threat of getting kissed by men… without someone forcing Sanji to train himself he’d end up way worse… with Mihawk again at best Mihawk would just tell Sanji to go outside and figure it out… with Rayleigh he’d tell Sanji to go fight those giant animals and Sanji would probably refuse, also since Sanji doesn’t have anything like G4, he would never actually manage to beat those animals, and of course he doesn’t have CoC so he wouldn’t be able to tame those animals
see each character got the exact type of training they require for their personalities… Sanji needs to FORCED to train and Oda chose homophobia as a motivation for Sanji… Luffy needs hands on day by day exact instructions to train because he relies on instinct in fights so he needs extra attention to focus on actual training… Zoro is the only one that is used to regular training on his own so the only thing he needs is to simply know what he is training at, and that’s why he’s the only one given a teacher who’s idea of training is simply telling Zoro to go and do the thing and then Zoro goes and does the thing
in conclusion, it’s likely all 3 would turn out worse but Zoro would be the least affected as long as he is at least informed on what to go train to achieve.