When traveling, the outline is easy! On the interstate, it's pretty hard to get lost, directions are simple, and not much time is wasted. Once close to your destination, all sorts of crazy can happen: passing streets, wrong turns, trying to find a good parking spot, and feeling out of place like something is missing -- that's where all the time goes.
Similarly, when writing, the outline is easy. The boundary conditions are the fun part. What's really maddening? Editing. Finding the right sound, the right wording, the right feeling. Almost always, its unsatisfying. It's never perfect, but it has to be done. It's holding onto an idea or feeling as long as possible without breaking, continuing to try to explore it from different angles to illuminate the fleeting moments that need to be captured. Mind wrecking, yes, fulfilling, rarely. The truth is, it's never complete, but it's as good as we could do.