My question is fairly simple, and pointed out after a number of facts, so please bare with me for the duration of this. And I'm putting this here due to Kakashi making the Chidori, and since it's the vastly related to the subject of contention, I thought it appropriate. If not, I sincerely apologize.
1) Minato originally forbade the use of the Chidori/Lightning Cutter due to the speed at which it must be performed causing a form of tunnel vision, thus leaving the user wide open for counterattacks from the sides.
2) This shortcoming was overcome by the use of the Sharingan, which see's everything regardless of the user's speed.
3) Certain characters are now able to move MUCH faster than Kakashi at any given moment, i.e., Naruto recently, Rock Lee, Might Guy, etc.
So... Why do they not experience any form of tunnel vision or blackout if they're moving even faster, and it's been established that at certain speeds, that begins to take hold?