User blog comment:Zolnir/RWBY Episode 3 Short Review/@comment-99.227.202.101-20130802183222/@comment-5217560-20130802183944

Only the First, mid finale, and season finale episode will be "long"(I.e. 11 minutes give or take a couple minutes). The rest of the season will be approximately 5.5 minutes or according to Miles and Sherry "varying lenghts".