I think splitting the straw hats into two groups for the WCI and Dressrosa arcs made a lot of sense given how many characters Oda introduced. Wano sucked because he wanted to keep introducing new characters at the same pace. The arcs got longer but the panel space was insufficient (or rather inefficiently used) to accommodate the number of new characters, existing characters and straw hats simultaneously. Characters like Usopp, Brook and Chopper received secondary roles (at best), while some of the straw hats who got their own fights still got too little screen time imo like Brook, Jinbei, Franky, Robin. I don't mind the idea of arc-specific characters getting 1-on-1 fights but Oda should have kept splitting the straw hats in order to smoothen out the arcs and flesh characters better.