The Rough Sketch

Some photographers stress the importance of sketching out ideas before shooting, so I decided to plunk myself down and do it too.  Everyone works differently, however my question is:  "Why sketch before shooting?"  Why draw when you already have the image you want sitting in your mind?

Perhaps the sketch helps choose lighting, camera angles, the placment of people, props, composition, etc.  Or, sketches may be helpful when sharing ideas with prospective clients.

I probably won't be sketching before shooting unless (for some reason) it is absolutely necessary, but I have to admit:  Drawing was fun. So...

If drawing a pre-shoot sketch helps you plan, then...by all means...do it!