Yeah Itachi managed to use genjutsu on Naruto because they were just standing and looking at him. But what i'm saying is that the 2 were attacking as well, so must had time to watch out the 2 of them. The time to cast a genjutsu to one, and he could have been killed by the other one.actually it would have worked better for him if he did use genjutsu, disable one, then by a touch of his hand he could suck them up , and what? itachi still used genjutsu when it was 5 v 1, i don't get your point
Just see it here:
-
You must be registered for see links
(just the time one throws the kunai and the other is already behind casting his jutsu)-
You must be registered for see links
You must be registered for see links
(Just the time Tobi has time to surprise one from behind, the other one throws a kunai)-
You must be registered for see links
(here they are two attacking from forward. One just get passed through him and the other is already there)As you see, he couldn't have time to take care of one alone that the other was already there. That make the use of genjutsu really difficult.