Some storyboard artists can get across information with only a stick figure however, being able to draw anything from any angle and in perspective is a huge benefit in being able to "simulate" what the camera will see and more efficiently communicate the ideas that the director wants to get across. (CinemATL)

Before you create your film storyboards, you have to perform certain tasks and make certain decisions. First, begin by evaluating your screenplay and picturing it in terms of separate shots that can be visually translated into individual storyboard panels. (Dummies.com)

Some directors were known to have had very elaborate collections of storyboards prepared for their movies, feeling it was essential to have most aspects thought out in advance of shooting. (The American Institute for Conservation )