Board Thread:General Discussion/@comment-4976518-20140808063123/@comment-10330822-20191026064700

I'm also of the opinion that complete hypnosis is the Bankai. Is it possible the hypnosis is conditionality on reiatsu levels though? Aizen is so power that perhaps his Shikai is enough to catch anyone in it, but the Bankai was supposed to enhance the effects to capture stronger individuals that the Shikai couldn't capture. And so as Aizen got stronger, the necessity of his Bankai deceased and ended up just being a waste of reiatsu as no one could resist his Shikai.

Aizen once told that Sui-Feng that effects of Zanpakuto that are usually reiatsu are dependent of reiatsu vs. reiatsu, and stronger reiatsu will always beat out the effects of weaker reiatsu abilities, like Suzumebachi.

So perhaps Aizen is the opposite, and his overwhelming reiatsu eliminated the need for a Bankai because it made his Shikai to overwhelmingly powerful and the Bankai not cost effective. After all, why waste excessive reiatsu hypnotizing people who can be hypnotized his with Shikai.