Kakuzu's capabilities with Raiton: Gian are far underrated by many members on NB currently. The potential of this B-ranked jutsu was equal to that of Kakashi using TWO Raikiri's, why would Kakashi need to use 2 Raikiri's against a B-ranked Raiton Jutsu? Personally I believe rank placement on all of Kakuzu's techniques are incorrect being "B-ranked" anyhow this is getting off-topic.
Here Kakashi had to use two Raikiri's (S-rank) to counter Kakuzu's Raiton: Gian; a B-rank technique.
You must be registered for see images
Kakashi then praises Kakuzu on how skilled he is in general, but referred heavily to how he used his previously displayed Raiton technique: Gian:
You must be registered for see images
I want you guys to pay attention to the boxed in words: High Caliber, Perfectly, and Lightning. All fitting words, in which will furthermore prove that Kakuzu's Raiton: Gian ability shouldn't be underestimated like it is now. Kakashi had admitted that Kakuzu mastered, and performed a high caliber Raiton-based technique (Raiton: Gian), he later in his praising sentence goes on about stating that in order to have performed such a high caliber jutsu Kakuzu must have mastered Raiton perfectly.
So if Kakuzu had mastered his Raiton nature perfectly, and was able to execute Raiton: Gian to be able to multiply itself to attack multiple enemies present (Shikamaru, and Choji) why exactly could he not execute more than two? I believe Kakuzu could emit a great amount of Raiton: Gian against a single, and/or multiple opponent(s). Take a look at this Databook Page:
You must be registered for see images
Not only does the picture above support the idea of Raiton: Gian multiplying into many spear-like currents, but it basically blatantly hints to the public that it is perfectly capable of doing such a feat. Pay attention to the underlined words: Multiple, and Convergence.
Definition of multiple (adj)
1) Involving several things: involving or including several things, people, or parts
2) Number divisible by another: a number that can be divided exactly by a particular smaller number
Synonyms: manifold, numerous, many, several, various, compound
I'll be using the mathematical definition for convergence due to that fact that I'm talking about multiplying Raiton: Gian.
Definition of converged (verb)
Mathematics
1) (of a sequence) to have values eventually arbitrarily close to some number; to have a finite limit.
2) (of an infinite series) to have a finite sum; to have a sequence of partial sums that converges.
3) (of an improper integral) to have a finite value.
Now yes, it is correct that Raiton: Gian has a finite (limit) however, it isn't measurable due to the dependency of the amount of opponents Kakuzu must be facing in order to determine the limit of Raiton: Gian. Kakuzu only multiplied Raiton: Gian by two because Shikamaru, and Choji were the only targets, and Ino was behind a tree so she wasn't in his line of sight.
In conclusion it is assured that however, many opponents approach Kakuzu Raiton: Gian would multiply, and instantly kill them all. Due to the limit of the opponents not being infinite (which is impossible) Raiton: Gian would strike them all due to its non-measurable, but finite limitations.
