Robert Southey describes his progress in writing the Tale of Paraguay, not published until 1825. He reports that as a boy he actually began writing a continuation of the Faerie Queene, which, alas, likely went up in smoke when he made a bonfire of much of his juvenilia when a student at Oxford.
If Murray and I part company upon this occasion, as I rather expect we shall, I shall give February to my tale of "Paraguay:" a couple of months will carry that to its close. It has gone on very slowly, one great reason of which is that I cast it in the Spenserian stanza, which stanza is exceedingly difficult for a man who is not satisfied unless what he writes will bear the test of a strict examination. Thirty years ago I could write it as rapidly as any other measure; and at that time I planned and made some progress in a continuation of the "Faerie Queene." The stanza, however, is perfectly adapted to the slow movement and thoughtful character of the story, and I am entirely contented with what is done.