User blog comment:B214/Season 3 confirmed!!!!!!/@comment-25120103-20141109121106/@comment-1359322-20141110142734

Other studios will complain though if DxD releases 14-16 episodes only. Small studios all take turn in releasing their anime each season. Spring, Summer, Fall and Winter, the four seasons are 3 months each, and every anime is 12-13 episodes which is around three months. Unless if the studio is producing 2 cour, studios aren't allowed to produce 14-16 episodes anymore, since it'll mess up the line up for each season. The only exception to such rulings are the long-term series since they are continuing for months and years.