From 1997 to 2004, Oda produced 349 chapters. He started writing One Piece at age 22. He started out with Romance Dawn and was halfway through Water Seven when he became 30.
During his 30s, he produced 431 chapters. He covered up so much. Water Seven, Sea Train chase, Enies Lobby, aftermath and the chain reaction to the timeskip, Thriller Bark, Saboady and Luffy finding himself alone and getting involved in the war, timeskip, Fishman Island, Punk Hazard and half way Dressrosa.
During his 30s, however, Oda's health was already in decline and was getting worse as he went through his 40s.
In his 40s, he produced 362 chapters. He made the most longest arc in the story that took four years to finish, Wano. He has to take 2 month long break and had an eye surgery. Over the years, he takes more and more breaks. I bet One Piece might even finish before he hits 60.
Between Romance Dawn to Drum island, Oda never took breaks. But over the years since Arabasta he would start taking breaks. It would at first be 5 chapters, then slowly go down to 2 chapters before break. Back in 2006, he manage to pump out chapters without a break from January to April until his break came back.
During his 50s, Oda would go even slower. If he has not taken any breaks, One Piece might even finish the series already.
Look at Wano that was full of missed opportunities, sloppy writing and how he was speedrunning the arc. He essentially skipped the middle of Egghead Island without exploring more potential. Heck, Franky wanted to meet Vegapunk but there is no development between the two and did not explain the Devil Fruit right like Oda said he will explain what they are and how it works. He is rushing everything but makes the end of each arcs sloppy and chaotic. The writing of Egghead was always back and forth.
Since the series is at the final stage of the story, it is painfully obvious that the story is going to end somewhere in his 50's.
He'll never beat out Charles Schulz where he continue drawing Peanuts until he was 82 years old.
The story is long enough and it is time to stop.