They're very useful for the boilerplate stuff and it's somewhat rewarding to type out 3-4 letters, hit tab and wind up with half a dozen lines in a bash script or config file.
They tend to get in the way more for complicated tasks, but I have learned to use them as a psychology trick: if I have writer's block, I just let them pump out something wrong since it's easier to critique a blob of text than a blank page.