I have used this technique to write at least one chapter from Return to Chernaya Bay but I am sure it also contributed to many other aspects of my writing in the book. In the chapter 17, titled "Nightmare", I used it and it really helped me create a character development and it brought a spontaneous and yet in depth insight about one of my main characters with the introduction of secondary characters.
I like the effect of having something totally out of nowhere triggering a whole creating process. One phrase, one idea, one question, one image can develop and inspire a chapter and take your story to an unexpected direction. I really believe it should be used and it can refresh your writing approach. For this chapter the prompt selected was implying to finish the writing piece with "What is going to happen to them?"