Re: Strongest of the Hidden Leaf: The Hyuga Clan FC
Well, simply put, if she didn't use it on Madara, it would he anti climatic.
Twice its been shown , and yet twice we have not seen it in use. Why? Build up and suspense. Kishimoto tends to show jutsus early on and than have them actually used in battle much later. For example, itachi using amaterasu or Naruto mixing kyuubi and sage mode.
Also, seeing as how this is the last battle she'll moat likely be in, she's bound to use it here. Bit on who then? Well, obito's a good guy now, and the only one's remaining are Madara and Zetsu.
I don't think she'll use it on either spiral or white or black Zetsu, because she's been fighting zetsus since forever, and her using this jutsu on them wouldn't make sense, since, as I said before, this Jtsu had been getting build up, so it's normal to assume it will do something big.