I think there were at least 6 arcs between Drum Kingdom and Ennies Lobby. EL arc is where Chopper's Monster Point came into play. Something that he had before the story began.
What matters to me is not the amount of arcs or anything like that, but the context of the narrative. I'm fine with not having a lot of fights for many arcs as long as the progression keeps some sense and credibility. My criticism to the NW in this regard is that we're already facing enemies of the highest level without a previous taste of what the Strawhats can do. There is no point of reference. Even for Zoro and Sanji. Everything about their current level is super vague… and yet we see power ups coming too, which is weird too...
That's why I think the comparison with pre-timeskip is not completely analogous. In particular, your example for Chopper doesn't make much sense to me, since his Monster Point was not something that he could control, just a desperate move before defeat, so it's normal that he never used it before. That's not what I'm asking for.
What happened for the most part of pre-timeskip was that some members of the crew were already pretty strong and above average since their recruitment, so they didn't face a real challenge until Alabasta, which made sense. But even before Alabasta we still got a good taste of their abilities and strengths. Arlong Park gave us a point of reference for the entire crew. Only Nami was the exception since she hadn't done much onscreen fighting beforehand (even her weapon was completely new, lol). And from Alasbasta we could keep watching their evolution step by step… so there was a good sense of progression.
In contrast to Alabasta, the crew didn't arrive at the New World already ready to face a Yonkou in the same way that they were ready to face Baroque Works. And yet that's what's happening...
A natural progression only happened for Luffy. First we saw enemies that were much below his level like Hody Jones and CC. Then we saw a worthy opponent like Doflamingo. Then we saw two guys that were above him, Cracker and Katakuri.
In comparison, Zoro only found opponents below his level... and most of the other Strawhats didn't get even that...
That's weird. Not because of how many arcs it has been without fights, but because they are about to go against the Leading Performers, the Tobi Roppo, the Numbers and whoever else... enemies that are supposed to be beyond what they achieved during the timeskip.
I see it like this, should G4 have been used on Caesar or Hody? Those enemies and their support weren't worthy of that. The crew need an opponent that makes sense to unload that. The progression would seem off if we knew all of the capabilities of the crew by now and this current battle is where everyone went beyond their limits (like Ennies Lobby/CP9) or just totally drained themselves (like TB/Moria). It's a Yonko, but the whole point to this is to liberate Wano. The clear difference is that I see post Wano as as a new beginning and most believe that the story is near the end.
Of course the Strawhats shouldn't use their craziest abilities against weaker opponents.
My point is that Oda should have invented some worthy opponents for them before Wano for us to get a point of reference of their level. Give one fight to Robin in Dressrosa. Give Franky a better fight in Dressrosa. Maybe give a fight to Nami in Punk Hazard (against Monet, maybe). Give a full-fledged fight to Sanji instead of those isolated clashes that go nowhere. And the list goes on.
Another factor is that Law illustrated that Yonko crew are vast. Larger and stronger than former opposition. It requires allies/numbers. So the focus has been on Law, the Fleet, Scabbards, etc. It builds the SH crew to be almost similar to the WB Pirates that had a ton of allies. Law has a bunch of crew members, but the focus is on Bepo, Jean, Penguin and Hachi. We don't even know the last 2's capabilities. It is different for the SH crew. Everyone gets focus. I believe that is the same philosophy behind the allies. When you see WB allies, Squard even got to play a large role. So, fleshing out Kawamatsu or Barto is for the purpose of us being familiar with an ally, which goes in line with how we knew the WB allies that were even main crew in the Oden flashback.
Not gonna dig into if this is great or bad. Just that I can see where he is going with it, so when the incident that takes place, I will be able to critique if it was worth it or Oda wasted my time by not keeping the crew as the focus they were for pre-timeskip.
That's another thing… and of course this focus on other characters is one of the reasons why the Strawhats got less of the spotlight.
That said, I'm not against this route that Oda has chosen. Nonetheless, I still think that even in this structure he could have found room to display the Strawhats a little more. In fact, the Strawhats did get a lot of screentime in PH, Dressrosa and WCI. Their screentime was just not optimal combat-wise.