So here's the thing about kabuki acts. And I say all of this with full admission that Oda can and will do whatever the heck he wants, in any form he wants.
And this is why it's problematic to run to a wiki, read a wiki, and think you know what everyone knows about a given topic.
What you're reading on the wiki about kabuki, is a breakdown by people who know the nitty-gritty details of the given topic.
Looking up "How many acts does kabuki have?" on wiki is not the same as asking Tarou Q public the same question. If you ask Rando J-Person how many acts a kabuki has, you're probably going to hear the answer 'three' as their best guess.
Because that's the most commonly known breakdown.
That's not to say it's accurate. Or that those three even represent what we call acts.
But Jo-Ha-Kyu is probably the best widely known organization of kabuki.
"But the wiki says…!"
Yes, and the wiki is correct. It's also a textbook vomit of data, not living public knowledge. And that's what Oda might be basing it on.
And all I'm really trying to say with any of this is, even if it is 5 acts, don't expect every act to be massively long.
In fact, things are going SO WELL here for Luffy and co. that it's almost wildly suspicious.
Yes, I want to see this end in misery and then a relocation.
But that also takes a lot of time to build momentum and Oda is Mr. Rush-it these days so I dunno if he's going to allow himself to do that.