Oda should have stuck with the originial idea and have Doffy be part of Wano as the Joker card, that way Law would get to finish him off, and have Dressrosa be a short arc taking care of his crew.
The moment we saw Doflamingo being scared of Kaido I wasn't ready to spend 100 chapters on a villain like that, imagine you build Kaido but have to wait fot another 6 years for his arc.