For some reason I feel like blaming noitamina, it seems like alot of series during that time slot are 13 episodes, the only exceptions are Honey and Clover and Nodame Cantabile first season. J.C staff tends to be quite nice with episode count, other then Zero no Tsukai, most shows lately they make are 26 episodes. So it could be Fuji TV forcing Pari-hen to be 13 episodes, everyone with a normal understanding of anime pacing, would know that Pari-hen should have been 26 episodes, there are perfectly enough materials to animate. Or Fuji-TV wanted to see how well pari-hen does before deciding giving it more episode count. The next season could also make audience 'look forward' to the two live action movies (first one out at December 2009 and the second one at Spring 2010). (I also blame Fuji TV for not allowing 26 episodes of Toshokan Sensou too).
I think J.C staff did best their at making this 11 episodes, although I still think the live action paris-special in the 4 hour format did a better job (they did skip quite a large arc). J.C staff made alot of little changes, but nothing major...so that's still better then Zero no Tsukaima right?
