All the vets say they have the experience to win over their younger foe. It is definitely a process. However, I think Hopkins got his PHD from RJJ. After that fight, he changed is game. A lot! If anyone hasn't seen his first televised fight it is a MUST WATCH! This dude did NOT like clinching. Yeah Hopkins. At 168lbs known as the Terror. Just a thrill to watch this fight. But after his loss to RJJ, he didn't stop being offensive minded, rather he embraced counter punching more, and fighting tactical which led to his masters in clinchology. This content is protected RJJ was always a pure talent, but according to him his wicked bodyshots were a result of his fight with Mike the bodysnatcher McCallum and it showed.
One fight can definitely teach a fighter a few things, dramatic changes in style are a result of behind the scenes work though. Fights can give a reason to adjust like you mentioned
I don’t really think Lomachenko has fought any other good fighters with Salido’s style. Not sure what changed about Joshua. He looked unspectacular against Parker.
personally, i don't think Joshua learned a thing in the Whyte fight. he just went out there and tried to batter Whyte from pillar to post
i didn't think that was what the OP was asking, i thought it was just the experience gained in one fight and i think the way he has fought since compared to that fight is night and day. and that was my point about AJ tbf. he seems to have changed his style since that fight, and he has mentioned a lot how much he learned in that fight and from Klitschko