Board Thread:Naruto Discussions/@comment-1043414-20140724205217/@comment-1043414-20140726170817

Still, it was shown that with the aid of Yin-Kurama, the period could for using tailed beast-mode could be extended. Similar to how Naruto couldn't continuously use Sage Mode without merging with one of the Sage Toads, instead using shadow clones to extend his time limit.