Board Thread:General Discussion/@comment-26912075-20160401141344/@comment-3423279-20160402210630

It might be that Byakuya, who I am fairly sure isn't an expert on all things Zanpakutou, just doesn't know.

Another possibility is that because Shikai is so easy to maintain compared to say, Bankai, or for the Visord, Hollowfication.

Kenpachi and Ichigo seem to just have enough power reserves that it doesn't matter to them, and Kenpachi not knowing the name of his Zanpakutou while in Shikai made it similar in some manner to Yumichika with his Zanpakutou.

Yumichika using the wrong name made it angry, and refuse to use its full power. For Kenpachi, having (unless Yachiru is his Zanpakutou) zero connection to his blade was probably far worse.