You're obviously not paying attention. This is Shirou wanking. Canon says Shiki wins.
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Yes. Think of it as speed that infinitely approaches instantaneous, but never quite reaches it. (as that would be Magic).
Hey, how many swords can Shirou throw at him? Shiki was killing masses and masses of beasts and even Unicorns and shit. He's fucking fast.
Besides, if it did get to many, just flash step away.