@Shangetsu
Because they're good doesn't mean that they can learn it overnight.
Come on. We've seen Yoruichi learning how to do that energy ball instantly(can exactly remeber what was that exactly, something about safe travel to the SS, guess they didn't have the Soul Tickets at time), we've seen Ichigo learning (not)bankai within days. Tessai and Hachi are Kidou's masters I think they are capable of learning that, this manga is all about quick progress. Add to that Yoruichi, Urahara(I know, unavailable) and some people that are kidou gods but we don't know about it yet.
I suspect trying to perfect that jutsu would be more useful than Hitsugaya's swordfight training @_@. And Nanao is kidou genius from now on. Probably that's why... she wasn't seen during Fake Karakura? I'm confused now x).
Han-yuu said:
We had discussion how Kubo disregarded this ability especially when needed, in earlier quincy invasion arc. did anyone properly used it when half of the captains lost their bankai.
Exactly, that's why it was so frustrating not being able to see actual fights at that time.