Why did The Lord of the Rings take 12 years to complete?
Tolkien was still teaching at the time, and there were also trivial matters in life constantly bothering and interrupting his writing, plus that his health was not always at its best. But most of all, it was because of his noted perfectionism. He would consider every word and sentence and there would be revision after revision until he was satisfied. The manuscripts of the abandoned versions were later published as the History of The Lord of the Rings.