User blog comment:B214/Volume 23 discussion blog/@comment-77.188.202.233-20170429150936/@comment-190.160.185.214-20170430052036

I doubt it's unstable anymore, since he can transform directly into it without a chant or countdown and completely skipping BxB, and so far he has never needed to forcibly deactivate it. Also Issei does most of his training "off screen" (don't know the term when it's on a novel), so saying he is not training Triana is like saying he doesn't brush his teeth because we don't read him doing it.