Jigsaw Narrative

Multiple narrators tell he story of Charles Foster Kane's life.  We see his life in a newsreel format, in Thatcher's memoirs, and as told by Bernstein, Leland, Susan Alexander, and even Raymond, the butler.  What is the point of telling the story in this way?  Does each narrator give a specific "spin" or have a particular bias?  Does each see a distinctive aspect of Kane's personality?  Is each section told in a different way, utilizing different techniques of filming (such as camera angles, deep focus, lighting, or even choice of music)?  What" bang for our buck" do we get from this jigsaw narration?  Is it equal to or greater than the sum of its parts?