yeah sure, but kamui is the 2nd fastes technique we've seen, before anyone is making something big enough kakahsi can warp him away, don't orget kamui is instant, kakashi can use it 3-4-5 times.
Shinobi can get creative, and it's only been "instant" when used on WILLING targets, kakashi even said himself he had to gather some when he went for the gedo's throat.
Right here we see kakashi activate MS
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right here is where he says he's got enough, 6 pages after he's activated it, kamui is in no way instant or broken, slightly OP, but with knowledge you can get around it and use it against him in certain cases.