Which is why i said below the less obvious the gen is; the longer it takes for them to realize it. Personally idk why the **** sasuke made his gen look so ****ing obvious with the feathers and crap.
If you look at sauce distance when he trapped danzo at the start
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To the point he made it obvious
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His distance is much closer and he had no fatigue issue.
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Yeah, i guess it's fanfic to say sasuke had enough time to finish off KB manga wise since we cant accurately figure the time. but logically his feats against danzo shows he can use gen the smart way and not fatigue himself to where he can still wield sword. Imo i think the reason is because kishi originally intended sasuke to have tsukuyomi which is known to have after effects as shown against KB where as GKS sasuke had only generic MS sharingan gen.
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The retconned sasuke gen would had given him the time to kill off KB.