Ask HN: What makes a documentation automation project succeed/fail?

I'm proposing a "mini case study" roundup, about what goes right and wrong with document automation. (That is, computerizing the paperwork. Think in terms of, "We used to do all this with paper forms...") I'm hoping to collect horror stories ("Well it sounded like a good idea at the time, until This Thing Happened") and smart-things-done, and turn it into an entertaining-and-useful essay about Things You Should Know. So tell me your horror stories and "yay life is simpler now" successes. I don't need to quote anyone, which I hope makes you more willing to share stories. (Private messages are OK. I'm more interested in storytelling and lessons-learned than in finger-pointing.)