so shin had only the sharingans for the looks

[GT Is Not Canon]

yeah but its like susanoo or ameratsu, everyone on the base hears sharingan they think they can use all the ultimate abilities, not even thinking about training or preparation needed for such feats

 

[Aznkidd]

Uhm, is there any one around to teach him that ?

 

[Styles]

"according to Obito and Danzo"



@bold proof? There is proof that Uchiha can do it without senju DNA but none for non-uchiha.

Increasing the time doesn't mean they can't use it Madara did it Itachi said other Uchiha did it so they made Izanami to stop it.