I've been writing 100 prompts just to keep my creative mind loose and active and also to give myself some story starts for the third novel. I had written a prompt in January on retreat that has stuck with me and I suspected it would be part of the novel, maybe even the beginning. But the very first one of the 100, called "Road Trip," turned into the beginning, and on retreat I started from it and wrote chapters. However, others of these prompts are seeming relevant. While I was on retreat this past month, I found myself writing more prompts around some of the characters and using those in chapters.
And I saw for the first time how this prompt exercise can more directly serve my novels by letting me explore issues for 10-15 minutes around the characters, their back story, their hopes and dreams, their obstacles and challenges, their families. I have about 20 more prompts to write of the 100 and I don't expect they will all serve the novel but I am open to that if it happens.
I've written before about Judy Reeves' marvelous Writer's Book of Days, which really got me started with prompts. Judy has put out a second edition with revisions and new prompts, so if this idea of short daily fiction appeals to you, either as a genre of its own or as a skill-building tool, I highly recommend it.