This significantly helps with the planning process of the story. You are able to pinpoint the camera angles you want for each shot, the expressions your character will have, and get a feel for the framing of each scene. This may not illustrate what the animation will look like exactly, but this gives you a very good feel for the sequencing. I am obviously not the best traditional artist, but these are simple tools to help when I bring all of this to the computer.
I like to remember back to a very simple, yet impacting quote one of my professors always encourages, "Think 8 hours, work 2."