Why is there a curious symbolic pattern of time used in 4 Nephi when nothing is reported to have happened?

4 Nephi 1:6 reports that nothing happened between the 38th year and the 59th year:

And thus did the thirty and eighth year pass away, and also the thirty and ninth, and forty and first, and the forty and second, yea, even until forty and nine years had passed away, and also the fifty and first, and the fifty and second; yea, and even until fifty and nine years had passed away.

4 Nephi 1:14 similarly reports that nothing happened between the 71st year and the 79th year:

And it came to pass that the seventy and first year passed away, and also the seventy and second year, yea, and in fine, till the seventy and ninth year had passed away…

Why would Joseph Smith report the time in this peculiar fashion?

41, 42 to 49
51, 52 to 59
71, 72 to 79

This method of reporting time uses the sacred number 7 which is used throughout the Book of Mormon, and fits well with Mormon communicating a message rather than relating history. Wouldn’t we expect Joseph to have reported time in a more typical way? Wouldn’t it have been unnatural for Joseph to have dictated it like this?

See:

Evidence Central – Book of Mormon Evidence: Symbolic Time in 4 Nephi

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