I must stress that you can tell a lot of the "higher" tier fights were skipped purely to avoid showing off those powers as of yet. The reason why we got a ton of Whitebeard at the time? He died in the same arc. Ace? Same fate.
Sabo? Jesus? Fujitora? Ryokugyu? Weevil? Payback War? etc etc etc. They will have their time.
Imagine this scenario: Oda draws a 10 chapter Payback War arc. He shows off 90% of what the Blackbeard Pirates can do, and completely shows off Marco, Joz and Vista's max potential. Now imagine Nekomamushi recruits most of the old WB pirates for Wano's war. Would you be as invested in those panels showing off their powers?
I for one am waiting for the "skipped" fights to pay off, purely because its clear that if it does not drive Luffy's personal story, Oda is saving their exposition for later in the story.
Despite this, Oda completely elongates every single arc Post-TS. I remember discussing this with Ndule in the Critics Club over a month and a half ago.
This is very true. Granted, the sheer number of side characters is also what elongates the arcs even more. Summit War had the benefit of only focusing on Luffy throughout most of it and only introduced a few important characters per arc. Dressrosa focuses on all 5 strawhats there at different focal points, as well as like 15 other named characters that would eventually become the SHF. Oda also spent a lot of time on characterizing Law/Doflamingo's relationship and the 13+ members of Doflamingo's crew.
I'm not saying this is a good thing in regards to pacing, but you have to give the man credit for even coming up and combining all of this together. I definitely would have liked arcs to be shorter, especially WCI (which nearly showed all 80 of her damn children lmao). WCI is even pooling into Wano it seems, especially with BM and her crew being present.
Edit: And yes, this is essentially Oda's main problem: He makes too many characters and too many plotlines.
I can only hope that whatever comes post-Wano, if its not final war setup, is actually smaller/more condensed.