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Which of the following sounds more natural?

Walk 3 more blocks down the street towards Shinjuko.
Walk down the street towards Shinjuko 3 more blocks.

In the phrase "walk a mile", is a mile a direct object or a contracted form of the adverb for a mile?
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All of these are fine, common and natural; placement of the adverbial here is not of the essence, and the utterance could come out in any of these forms without any real change in emphasis, though emphasis tends to be, if anywhere, at the end of an English sentence:

Walk 3 more blocks down the street towards Shinjuko.
Walk down the street towards Shinjuko 3 more blocks.
Walk down the street 3 more blocks towards Shinjuko.

In the phrase "walk a mile", is a mile a direct object or a contracted form of the adverb for a mile?-- I don't see those as mutually exclusive. With omissions or additions, the functional descriptions of sentence parts change.
Comments  
"Walk three more blocks down the street towards Shinjuko" is more natural.
And in the phrase "Walk a mile," the word "mile" is the direct object.
 Mister Micawber's reply was promoted to an answer.