The cause of this catastrophe? Turning a deaf ear to a character's wishes ~ and the consequences were ugly, very ugly.
Dallas Keegan, my main character, was telling me to slow down and follow her lead. Did I listen? Nooooooo! I kept telling her, "Quit bugging me, I know what I'm doing," and continued on my merry way -- confident I would be finished with Volume III in record time. It wasn't until the 6,500 word mark I stopped to do a pre-edit review. I realized the path I was on had too many detours and would thoroughly confuse the reader (it already confused me).
So ... I wore out the delete button on the keyboard and ended up with a mere 4,000 words and a case of the (albeit temporary) 3 D's: Disappointment, Defeat and Discouragement.