Would Joseph Smith have spent around 450 hours engraving the characters on the plates?

In addition to the estimated 480 hours needed to hammer out the plates, Joseph would also have needed to engrave the characters. Eyewitnesses and others described the engravings:

“[The plates] were filled with . . . Egyptian characters. . . . The characters on the unsealed part were small, and beautifully engraved. The whole book exhibited many marks of antiquity in its construction and much skill in the art of engraving.” — Orson Pratt (Journal of Discourses, 7:31, 2 January 1859.)
“There were fine engravings on both sides.” —John Whitmer (John Whitmer to Theodore Turley, “in the presence of his anti-Mormon friends.” As reported in Richard L. Anderson, Investigating the Book of Mormon Witnesses (Salt Lake City: Deseret Book, 1981), 131.)
“We also saw the engravings thereon, all of which has the appearance of ancient work, and of curious workmanship.” —Eight Witnesses (“Testimony of the Eight Witnesses.”)
“[T]he characters . . . were cut into the plates with some sharp instrument.” —William Smith (William Smith interview, The Saints’ Herald, 4 October 1884, 644)
“Upon each side of the leaves of these plates there were fine engravings, which were stained with a black, hard stain, so as to make the letters more legible and easier to be read.”— Orson Pratt (Journal of Discourses, 7:31, 2 January 1859)
It [Joseph’s transcription of characters from the plates] consisted of all kinds of singular characters disposed in columns, . . . Greek and Hebrew letters, crosses and flourishes; Roman letters inverted or placed sideways were arranged and placed in perpendicular columns, and the whole ended in a rude delineation of a circle, divided into various compartments, arched with various strange marks, and evidently copied after the Mexican calendar.”— Charles Anthon (Letter from Charles Anthon to E. D. Howe, 17 February 1834, as printed in B. H. Roberts, ed., A Comprehensive History of the Church of Jesus Christ of Latter-day Saints (Provo, Utah: BYU Press, 1965), 1:100–101.)
“The characters were arranged in columns, like the Chinese mode of writing, . . . Greek, Hebrew and all sorts of letters, more or less distorted, . . . were intermingled with sundry delineations of half moons, stars, and other natural objects, and the whole ended in a rude representation of the Mexican zodiac.”— Charles Anthon (Charles Anthon to Rev. T. W. Coit, 3 April 1841, as printed in B. H. Roberts, A Comprehensive History of the Church, 1:101.)
“[Martin Harris] was in the habit of exhibiting to his hearers what he claimed to be a facsimile [sic] copy of the title page of the forthcoming book [Book of Mormon].” One who saw this copy said, “On it were drawn rudely and bunglingly, concentric circles, between, above and below, which were characters, with little resemblance to letters.”— Charles W. Brown (“Manchester in the Early Days,” Shortsville Enterprize [sic] 35 (ca. 1883), based on Orsamus Turner, History of the Pioneer Settlement of Phelps and Gorham’s Purchase, and Morris’ Reserve (Rochester, N.Y.: Alling, 1851), 215.)

Kyler Rasmussen estimated that it would have taken around 450 hours engraving the characters. This takes the total time needed to nearly 1,000 hours for Joseph to create the plates. No doubt he could not have spent a four-week period working full-time on them, so the entire process would have taken a very long time to complete.

How likely is this to have happened? What motivation would Joseph have for taking so much time and physical effort in creating a fraud?

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