He will use it when the time is right, because Sage Mode is in some aspects so much better then Kyuubi Mode. I mean Frog kata looks so beast, maybe for close fights he will use Sage Mode, he should not rely on Kyuubi Mode, I posted earlier somewhere else.
Strong oponnents: Sage Mode first for analyzing and ending it with Kyuubi Mode
Weak oponnents: Kyuubi Mode (just going all out as a beast rasengan here and rasengan there lal)
Strong oponnents: Sage Mode first for analyzing and ending it with Kyuubi Mode
Weak oponnents: Kyuubi Mode (just going all out as a beast rasengan here and rasengan there lal)