First EE took less than 30 seconds to complete. Madara commented on how it wasn't enough. Gai noticed it as well. So Gai most likely used it once more during Naruto's talk with Hagoromo to confirm whether there was a point in using it further or not. Then he switched to Night Moth.
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Gai used repeated EE so unless you can show me the off paneled feat that led to both parties looking like this
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then your words don't matter. He most likely using it once more is your assumption but one thing we know is that during the talk, the fight was still going on.
And 'dream sequences' inside one's body were shown to bend laws of time many times before. The fight with Madara took most likely less than 2 minutes. So no, Gai isn't outlasting Danzo.
Dream sequence? One thing we know is as long as the talk was going on, they were still fighting. That's all.
If not, Gai and Madara should be looking in that same state when Naruto's talk just finished but we had them looking in an entirely different state exactly when the talk was over with us seeing Gaara and Kakashi were worn out as well.
Notice the difference in his Pressure points when he resorts to NM
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He focuses everything on it and this technique is far stronger than EE. Meaning there's more room for him to use Multiple EE while in the 8th.