He's not really struggling though.
First time he's really trying and all it took is to remember what Mihawk said that particularly random one time.
I'm pretty surprised someone like Zoro, of all people, didn't try to master this from the get-go.
He faced stronger opponents than this clown. He had many opportunities. I don't buy the convenient memory loss. Like come on... A dude who wants to be the world's best swordman since he's 8 forgot this crucial piece of information ?
Just wait for his fight against Shiryu. It will be the same thing but with observation Haki + the struggle.
The reason I'm personally getting impatient is that I know exactly what Oda will do since he does the same thing over and over and over.
One arc, one color of M&M. Same chocolate, different shell.
Oda is that teacher who spent his 5 first years preparing his lessons like a maniac, then spent the next 25 years reusing them with just a few tweaks here and there. And I feel like I’ve been held back 25 times.
It was so cool back then, now it's oozing laziness.
And I blame the Sanji and Zoro stans and powerscalers for all the time Oda wastes "developing" them at the expense of the other members of the crew.
I'd rather get some lore instead of predictable fights involving underwhelming characters.
I'm trying to not be too picky as far as character development is concerned.