And Yeah, I get Kakashi is a prime example, but in all honesty we don't know why he doesn't really use those other 1000 jutsus. And for that matter he uses basically the same jutsus for the most part. It could be possible while the eye remembers the jutsu if he doesn't recall it, he can't use it. Either way, it doesn't really make sense if Kakashi copied 1000 worthless jutsus. Why copy all these apparently weak useless jutsu? Because they're unique?
Even if he only copied 10 useful or powerful jutsu, why not ever use them in 500+ chapters? I'm going a bit off topic but The same applies to the jutsus in a village.
I can get most of these other suspicious villages but in the cases of the Raikage's, or (Yeah), but in dealing with the Leaf village specifically, they have only had few betrayals, with the majority seemingly recently. With them constantly preaching about the will of fire, I am surprised Every1 would be that suspicious of nearly every1 they plan to give their will to and for. Wouldn't the "will of fire" push them to make as many of their future as strong as possible?
Plus "a technique that can end the world", none such thing really exists, so it's not like I'm expecting that. But it's more like what Kakshi and Jiraiya did in the 1st place, but in a scale for the whole village, if they see it as possible for some individual ninjas.