How do you called the feeling of starting an arc in an island and nothing making sense and the crew being completely lost, till progressively more and more is revealed and you actually know what's going on? I'd say it was specially prevalent pre timeskip, like in Skypiea or Thriller Bark, but post timeskip also has given us the start of Zou or Elbaph.

Mystery Piece? Adventure Piece? It's definitely one of the highlights of the series for me, it's specially good when not reading weekly