[Krono]

Originally Posted by Acadia

Still somewhat cautiously hopeful this isn't the last season of Fairy Tail due to lack of spoilers any other upcoming arcs. Either that, or they had enough material to do two full seasons for this arc.

Spoiler for Arc Length:

By my estimates, at the current rate, the arc will conclude with episode 68. Add an episode or two for transition, and maybe a filler episode or two, and they're pretty much at the point for the next opening anyways. Faced with the choice of 1-3 episodes with an outdated opening, vs 9 episodes with an opening for the next arc rather than the current one, it's not all that surprising that they opted to have the new opening be for the current arc.

They probably would have done this before as the Tower of Paradise and Festival arcs aren't that much shorter than the Oricon Seis arc, except that by the time they reached those arcs, they were averaging 2.5-3 chapters an episode in order to meet their episode 48 end mark and still cover said arcs. Now that the series has been extended and they can go 2 chapters an episode again, this will occur more often when they reach the point of their next opening/ending.

It's also not just a matter of them deciding when to change the opening/ending. It's pretty clear at this point that a decision was made a while back to change the op/ed every 12 or so episodes (possibly a contractual obligation at this point).