According to John Sorenson, the statements, "thus they did encamp for the night" and they "were weary because of the greatness of the march" (Alma 62:35) might lead one to think that the entire operation since Moroni attacked the city of Nephihah took place in a single day. If but a single day is indicated, then the total distance starting from Nephihah and progressing "from city to city" and going "down by the seashore" until one reached the land of Moroni, could hardly exceed twenty-five miles; the part of that total distance which was parallel to the coast (from Moroni to Morianton and Lehi) could not have been more than fifteen miles. (Source Book, p. 285)
From this and the preceding verses, one could now estimate the total distance from Moroni to Bountiful along the coast of the east sea. Bountiful to Mulek was on the order of 10 direct miles (not parallel to the coast). The distance from Moroni to Morianton was unlikely to exceed 15 miles. The only other cities said taken by Amalickiah were Omner and Gid. Gid might have been inland from Mulek (Helaman 6:10), so the north-south distance between them might have been slight. If so, it is unlikely that from Gid/Mulek to Morianton would have been longer than 20 miles, based on the intervals between the other cities. Thus, the whole east coast area from Bountiful to Moroni that we can account for might have been only about 60 miles. Allowing for error we could say 65-70 miles. From the city of Bountiful to the boundary line with the land Desolation might add another 10 miles or so, but even then, the entire Nephite east coast would only be about 80 miles long. If this distance is near correct, then it would have been understandable why Amalickiah would think that he might be able to succeed using this route, and why Chief Captain Moroni was determined to defend this sector. [John L. Sorenson, The Geography of Book of Mormon Events: A Source Book, F.A.R.M.S., p. 286]
According to Joseph Allen's geographical setting, more distance between the city of Moroni and the city of Bountiful could have been involved.