Arcs are Organized in Parts (Volumes), not Chapters,
Part 1 is almost always "Arc Introduction" & We are already Done with that the moment Holy Knights Teleported to the Castle,
After that, usually Part 2 is about dealing Cards & putting everyone in Position to establish what is this Arc's Main Plot,
Elbaph Arc also already Finished this, as Part 2 focused on Loki Situation, it was Over with Last Chapter,
Now, We should have Part 3 focusing on Elbaph Flashback obviously,
Explaining why We are seeing these Characters Arc & why They are gathered together,
After that, We should have Part 4 focusing on Stopping that Threat that was established in Part 2 (Holy Knights, Kids, Monsters, Fire ... etc),
At the End of Part 4, We should have some sort of Conclusion to the Struggle or Introduction of an Element that takes Arc in a New Direction,
Meaning either Holy Knights succeed in Taking Kids or Capturing Loki, or We have Luffy/Shamrock Meeting or Someone arrives such as Man With Burn Scar ... etc
Depending on that Outcome, this Elbaph Plot takes about 4 Volumes (2 Already Done).
If any Part is Finished in like 5-6 Chapters, then the Pacing will look too Fast, while if it takes almost Two Volumes then it's too slow.
So far, the Pacing doesn't look like either, it's Fine.