Oda's current schedule is 3 weeks on then one week of break to stop him from overworking. The problem, especially with this arc, is he insists on drawing anything that moves, so with so many characters in the arc, he's drawing even more. The other problem is he only sleeps like 3 hours day because he says he can only think of great ideas when he thinks about them a lot without eating or sleeping, because he can only come up with new ideas when he's at his limit, so each week when he turns the chapter in he's exhausted. Here's the interview where he says that
One website posted this though "To assuage any potential fears fans may have, sources reassured us that this visit (to the hospital) was a scheduled break and not a sudden development due to overworking as was the case for last years’ sudden hiatus."
http://orojackson.com/threads/eiich...nga-to-be-on-break-for-the-next-2-weeks.3862/