User blog comment:Fliu/Chapter 947: A Small Step Forward and a Lucky Break/@comment-2600:1702:3C50:A6E0:BD34:D5D1:3583:F0E9-20190628121311/@comment-2600:1702:3C50:A6E0:DDB5:6010:6333:7037-20190629052852

Unless there is a similar time displacement as the one that exists in the Hyperbolic Time Chamber, I highly doubt that Oda will be able to do that. The Strawhats can't exactly stay in the prison indefinitely, they will need to leave before Kaido comes to try and kill them. While I am sure that knocking around the prison staff will help them, I doubt that they will find themselves getting a year's worth of training in one day.