So Sakura is currently healing thousands of wounded soldiers without any indication that her chakra is still being allocated to Katsuyu's pieces or that she's being strained by the effects of her technique? She's just standing about on Katsuyu watching the fight before her eyes with a tranquil expression. I don't believe that has ever been depicted as being possible by anyone.
We have a warped sense of time related to the chapters.
http://www.mangapand...m/naruto/635/16
The moment Naruto and Sasuke were attacked by the Juubi again, right afterwards Sai talks with Sakura. Let's say the whole conversation between the 2 lasts 10 seconds.
http://www.mangapand...m/naruto/636/18
Naruto and Sasuke didn't really start to defend themselves and Naruto spots Obito.
So these 2 events may have happened in just under 1 minute.