@attackmybutt replied to your post: Another way you can tell Bleach wasn’t planned…...
Shinigami drill to fight Hollows: why would you practice a move that permanently seals Shinigami powers with any regularity? Byakuya also doesn’t seem like the sort to publicly train, to train subordinates, or to do either with anti-Shinigami techniques. (Byakuya’s arrogance prior to the end of the invasion of Soul Society leads one to ask if he’d ever bother with anyone beneath him, even in a sparring match or training duel. Also, recall how shocked the 10th Division’s basic training guy was when Hitsugaya showed up in Chapter 538 to do basic drills?)
Furthermore, Renji’s implicit assertion is that most Shinigami couldn’t follow him. So, even if you assume he’s constantly been demonstrating the move, it just shifts the question: who would he have been teaching, and/or why was he practicing a technique to depower Shinigami out where he could be observed doing such a thing?
Does he just constantly flit around the 6th Division almost stabbing everyone and only Renji can see him even doing it?