Don't get me wrong when I was younger I probably watched the first 300-400 episodes of One Piece more than once and enjoyed it repeatedly. The pacing was occasionally bad back then but not a total joke. It's the subsequent 600+ where its lost the plot lol. One Piece is tied together by awesome, emotional, gut-punching backstories and takes exciting leaps forward in the story where other series would just stew for a while. So when you spread those key moments out to be 10, 20, even 50 episodes apart, it loses all its rhythm.