Board Thread:General Discussion/@comment-24815992-20140426145103/@comment-24867665-20140427002456

They were at full-strength, but I do think most captains didn't use Bankai so they could fall back on it as a last resort as it might take a lot of strength to do so [Edited by accident of spoiler, sorry].

Some captains' Bankai states could also be too overwhelming, like Yamamoto's. Don't want to be releasing something that might end up destroying the pillars as well.

=)