I usually know the big event at the beginning that gets the story started and then the big climax at the end, but not so much the middle. I used to just go with the flow, but now I'm more of a planner; I kinda outline as I go, so I always have a direction, a point B to get to.
That said, my story Secrets of the Heart that I started a couple years ago and never update, is outlined literally chapter by chapter because I had to piece it all together to make sure it would work, and I never have much inspiration to work on it. My new story, Guilty Roads, was planned up to a point before I started it, and now I'm past that point and don't have anything outlined beyond that. I have a general idea of where it's going, but nothing set in stone, and that one I've been a lot more inspired on. So I think sometimes it is better to just go with it.