Because we've already given it the full run a thousand times. As I said, there comes a point when doing any strike at all, repeatedly, becomes a chore, which is what the bounties should be called. Daily chores. When you've already fully done the little there is to do, you find ways to expedite the process and avoid the tedium.
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While I agree with OP (I like to kill through) I can see and understand your point. Our daily chores are quite repetitive and I can see how, after a while, running through would be the better option.