I’m pretty lousy at estimating writing project sizes. I’m pretty sure it’s because I don’t plan them out very well up front.
That’s why I made the conscious decision to focus on short stories in the near term. I try and target 5,000 words or so for my short stories, but one I have currently under way could turn into a novel if I wanted to take it in that direction. Oddly, the more I think about extending it, the less interested I am in adding to it, because I start to think I need to re-write the first 2,000 words and lay things out more deeply than I have.
I have four and a half current projects under way. Two short stories, a novella, and a novel. There’s a short story that I should be starting to write, but I’ve been putting it off because while I know where I’m going to begin, I have no idea how it’s going to end, and this is totally blocking me from starting.
Oh well, time to start bleeding.
Heather Kilbourn 
That’s the trouble – this stuff shifts around between the brain and keyboard!
I enjoy the planning stage for short stories and novels. I need to know roughly what will happen, but the characters can take me in a different direction. If they shout loud enough. 🙂
When I write a novel, I always need to know how the story will begin and have a vague idea of how it will end before I start to write. Everything else is always a surprise!