Board Thread:General Discussion/@comment-3244769-20160228202309/@comment-1604252-20180803100353

A shinigami has to train for ten years after achieving bankai to master it, before being able to effectively use it in combat. She most likely attained it before or during the series and mastered it while with the Royal Guard. Highly unlikely she just got it as a result of training with them. If so, every other lieutenant might as well have gone to the palace too for a free bankai.