Board Thread:Naruto Discussions/@comment-24824148-20160724215526/@comment-734582-20160730122033

Please, everyone, stop assuming so much and start looking at facts.

Kakashi used his MS a couple of times, true, but he did so in controlled fashion and used it only as a last resort. By the 4th war his eye had lost most of it's light.

Itachi used the MS not as a last resort, but most definitely was aware of it's cost and calculated accordingly. His Susanoo was so rarely used that Sasuke wasnt even aware of it, even though his Amaterasu was almost legendary.

Sasuke did spam MS techniques, but not his Amaterasu but rather his Susanoo. It's not that Sasuke after 3 uses loses sight (though he immediately notices the price), it's that he repeatedly uses it for Susanoo.

Therefore, there is a clear trend that indivudial MS techniques can be used dozens of times, or an equivalent time in Susanoo minutes. Itachi used his MS mostly for it's techniques. Sasuke used it mostly for it's Susanoo. Kakashi used it solely for Kamui.

Finally, early in the series it's made clear there's an efficiency to using techniques, and it takes great control to do it efficiently. Naruto is very inefficient but has a lot of chakra. Sakura can do so very efficiently and Sasuke was inbetween. We don't know Kakashi's exact proficiency, but it's clear that a transplanted Sharingan is very inefficient at first, but as Kakashi learned to use it, he got better with it. He needed quite some time to awaken it first against Deidara but his second attempt (at the explosion) was noticeably quicker. Against Pain it was still a costly technique but he could enact it fast enough to Kamui a small nail unnoticeably. In the 4th war he was approaching (But probably not matching) Uchiha levels of control. He could activate it quickly, use Kamui in various ways. Kurama gave him chakra (which is known to have strong healing properties) that allowed him to use Kamui to a much greater extent, and would likely have delayed (but not stopped) further degradation.

Furthermore, Kakashi was unaware that his eye was an MS until much later, which may hint at why his eye was so costly, and why he was so poor with it initially.

TLDR:

The known users of MS could use the individual techniques a lot of times. Sasuke relied more on Susanoo. Kakashi got noticeably better at using the Sharingan. There's no plothole.

Final thought: Hashirama's cells are so OP because the world suffers from genetic degradation and weakening of bloodlines. Hashirama's cells however are the result of fresh genetic material (via Transmigration) from close to the origin of all higher power. This has been, by the way, a fact since the very beginning: the Byakugan was said to have faded from many other clans, and many Kekkei Genkai were wiped out in the Hidden Mist.