@Señor:
Has Oda ever taken breaks for research (As well as Vacations)?
As far as I know, Oda took a break for compiling data on a famous shipyard (Mitsubishi Heavy Industries) in Nagasaki in October 2002 according to the author's comment. He said "it is the preparation for an upcoming series" which probably indicated Water 7.
Oda also took a break for 10 days' vacation in the US in March 2001. The photo of the souvenir from US is printed in ONE PIECE BLUE. He says he was about to conflict with the Washington Convention
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Relatively recently, he took 4 weeks' breaks for vacation in Hawaii in 2010.
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I hope Oda will take more breaks…