Short stories are a different beast from longer works. They don’t demand as much as a novel but they still they take up a lot of your time. I don’t know what makes a short story, how an idea becomes limited to a couple thousand words. I suppose it depends on how long my interest last, but I believe there’s more to it than that. You sort of know when it is a shorter work because often, the characters aren’t going anywhere (sometimes they do) and there’s nothing major to say. It almost feel like a brain dump, a well earned rest from the gigantic work it takes to make novels. I like to touch up on my style in shorter works, it allows me to pay more attention to the words I use and in which order I put them. Short stories aren’t as daunting either and usually the characters don’t make a fuss and go obediently to point A to point B.
The Horrors of Writing 