I don't think they ever put too much detail on the fight pages.
They never do. Let's take the 2 latest examples, Luffy and Zoro:
- Chapter 1,035: "Zoro Vs. King".
- Collection of mini-stories for the covers number 25: “Escaping from Whole Cake Island”.
- Queen has been defeated by Sanji's attack.
-Zoro realizes that when the flame on King's back disappears, he moves much faster but his defense decreases.
- King's face is revealed.
- Black wings, gray hair and brown skin, those are the characteristics of the Lunaria tribe. If someone informs the Government about them, they will pay you 100 million Berries.
- Flashback of the moment in which Kaidou and King meet. They were both at a government research facility.
- King's real name is Arbel / Albert / Albel (romanization is not clear yet).
- Continue the battle between King and Zoro.
- King uses an attack called "Omori Karyudon" and Zoro a new attack called "Dragon King of the Three Flames" or something like that.
- The chapter ends with Zoro attacking King.
The part I bolded is like 10 pages of fighting between Zoro and King. The 5 lines above it are from literally different 3 pages only.
Then you have Luffy vs Kaido last chapter:
Chapter 1,037: "Shuron Hakke".
- The end of the festival is approaching in the "Capital of Flowers".
- Luffy Vs. Kaidou.
- Kaidou drinks sake during the battle.
- The "Shuron Hakke" seems to be a technique of Kaidou being drunk.
- Alcohol makes Kaidou go through several phases in his fight against Luffy: sadness, crying and anger.
- Kaidou: "“ Gundari: Ryuseigun ”!!!"
- Luffy: "" Gomu Gomu no Roc Gatling "!!!"
- We went to the "Castle of Pangea" in "Mary Geoise".
- The "Gorousei" talks about capturing Nico Robin.
- We see Government warships near Wanokuni.
- Someone from the fleet informs the "Gorousei" that they are seeing a shadow.
- The "Gorousei" says that it is not possible, that even for them it is a legend, and that it had not awakened in the last centuries.
- The "Gorousei" ends up talking about a Devil Fruit and that they have given that fruit another name to hide its true name. [According to the Korean leaker it is not the Gomu Gomu no Mi]
- The chapter ends by revealing the identity of that shadow seen by the ships in the Wanokuni Sea.
- The shadow belongs to something / someone gigantic.
Part I bolded, is once again, like 10 pages of fighting.
Now take a look at this chapter:
Chapter 1038 : "Kid & Law vs Big Mom".
- On the cover, Yonji and Niji have been trapped by Big Mom in the Mont d'Or creature book.
- Raizou vs Fukurokuju, both are burning but they don't release their jutsus.
- Chopper is worried about Zoro and the adverse effects of the Mink's medicine.
- In front of Zoro appears a skeleton with a large scythe.
- Izou has defeated his enemies but the CP0 appears.
- It seems that they leave him aside because they have urgent matters to attend to but Izou stops them.
- Yamato tries to stop the fire demon by attacking it directly.
- Kid & Law vs. Big Mom.
- It seems that at first Big Mom had defeated them.
- Big Mom walks towards where Kaidou is but Kid and Law attack her again.
- Kid & Law: "Listen, old lady!!"
- Kid & Law : "Even if we die, we won't let you get to the roof!!!"
You can see that the way this is described, it "seems" that Big Mom defeats them at first, but they get back up and attack her. 2 things:
- We have no idea if there is fighting before the scene where she defeats them
- We have no idea what constitutes attacking her. Did she fight back? Did they do multiple moves?
The chapter is named after them. I'm not saying it's 15 pages (impossible), but I wouldn't be surprised if it's 8-10 pages of fighting until next chapter or the following. Each of the other scenes described sound like 1 pagers, maybe 2