User blog comment:Lia Schiffer/ANIME SPECIAL: 248: Dragon of Ice and Dragon of Flame! The Strongest Showdown!/@comment-1590714-20091213074020

That pretty much bothered me too. They never opened a Senkaimon unless Ichigo just took the same Senkaimon as Muramasa (like, forgot to close XD) and Rukia had the real Senkaimon opened up in the Seireitei. Otherwise, Ichigo would have needed the ability to make his own Senkaimon.