That and if they don't like the way some things look or sound they have to redo it again. Naruto Shippuden is not only going to air bu-weekly but it will also have more hour long specials not like episode 1 but back to back episodes where it will show the previous episode and then the new one.
Like episode 1 then episode 2. Two weeks later it will show episode 2 and then episode 3 for those who may have missed episode 2 or people who just want a recap before moving on. Another plan is airing it like Naruto was.