Five years ago our family bought a 35 foot RV and decided to spend our vacations seeing National Parks. It was, and is, a great plan. The problem arises when you try to navigate a 35 foot RV through the crowded streets and low over passes of small town USA, without a map. Take it from me, it's not a good thing. After two years of narrow escapes, and too many close calls, we've come to realize that mapping the trip out IS a good thing. It allows you to see overpasses that are too low, streets that are too narrow and places that don't provide parking for your house on wheels. The same is true when writing your novel. Mapping it out, before you begin, and revising as you go, allows you to spot those pesky trouble areas long before you are letting the air out of your tires so you can get under that bridge. Who knew that those Caution Low Clearance signs really meant low clearance?