Maps really help the writing process. Robert Louis Stevenson famously doodled a map of Treasure Island before he wrote the book. Crime novelists sometimes even include maps as part of the story- I’m thinking Jeffrey Deaver here- but that isn’t where the real utility of map drawing lies.
When you have a single location where a lot will happen- say a large house or a small town it’s great to have a map so that you can get everything clear before you write. You can even add photos to the map if it’s of a real place, but the map itself should be hand drawn so that you can include all the details that will make your world come alive.
Writing is about creating worlds and a map is a blueprint for such a world. I used a map, or plan, of the bunker complex the hero was trapped in, in my novel Dr Ragab’s Universal Language. The bunker was quite simple but a lot went on there and it really helped clarify – and make real- the story when I had the plan in front of me. It also helped when I had to describe the bunker in modern times as well as the 1930s.
The map can be huge- with photos stuck on as I said- though I find a single A4 is usually good enough for my purposes. I go through a few drafts to get my map correct and add things to it as I go on. Maps are good aids to plotting because you can map a journey and see if it makes sense timewise. You can mark where people are at any one point and see if your plot moves work. The other big benefit is by looking at the map you can bring in elements to the story you might have overlooked- that great oak in the corner of the field, or the disused bomb shelter at the bottom of the garden.
Nabokov suggested that a keen reader should try and draw a map while reading a great book. He gives examples of maps he drew based on Jane Austen’s Pride and Prejudice. It certainly breathes some air into the reading process. It also gives you an idea of what kind of detail you should put on your map before you start writing. It’s similar to getting an idea of what an outline should look like by making one of a favourite book you’ve read.