I have been drawing maps as a form of outlining, as a form of checking up on the movements of characters, to check myself, to answer: Could they meet in time? How far would it be there and back? Where was he went he wasn't with them? Several modes of travel are involved. This page on travel in Jane Austen's time has been so helpful.
Seeing the maps makes me see everyone's movements all at once. I can see where there are breaks, even when scene after scene tumble along just fine in the MS, with characters popping in and out like actors on a stage, who were just waiting in the wings.
It is fun to draw maps--the composition of oceans and continents, finding this wiggly hand-movement that makes shorthand "coastline." I look at maps-- from google earth to an historical atlas. I love novels with maps. (This one of Chalion helped me keep all the countries straight.) I love the way they are drawn. (Earthsea like a medieval woodcut, Middle-earth hand drawn with pen and black (and red!) ink, the Wood in Carson Ellis's folk art style.)
For me, the geography comes out of the story. There is an ocean because a character is to be shipwrecked. The strange place where she lands, where she came from and where she was suppose to go all come into existence at the same time. (I have been making family trees in the same way. These two characters are cousins, but have different last names, how?)
I have these empty continents, which make me think of the empty map in the Name of the Wind and I wonder if Rothfuss has his own filled in version for reference. Sure maps can be spoilers. There are two maps that appear as props in the MS. I think about drawing them, how I might draw one for myself and then make an edited version for the illustration.
Of course, there are maps that can't really be drawn, though a prop master can try. But it is a sort of testing, that I do with my map drawing, a questioning, a prompting that make me look at the story