Paul H. Dunn teaches that the Journal of Discourses and other prophetic writings contain examples of leaders "speaking personal opinions" but are sometimes mistakenly quoted as revelation by Church members.
Paul H. Dunn, “Truth or Speculation?,” address given at Provo MTC, 1990, 2-3, repr., Dennis B. Horne, Determining Doctrine: A Reference Guide for Evaluating Doctrinal Truth (Salt Lake City: Eborn Books, 2005), 22
The Journal of Discourses and other prophetic writings are delicate, because oftentimes you have a prophet, particularly in yesteryear, who is speaking personal opinion which today gets quoted as “thus saith the Lord.”