From American Cinematographer, Camera Technique Dominates Filming Results by Claude W. Cadarette (January 1940)
Every movement of the camera must have a definite purpose behind it, and if it is done without a good reason you are just retarding the tempo of the picture.
note from ryan: This is not something I learned today, but a truth that was retold from an article written over 70+ years ago! It's quite frustrating that such advice and wisdom has been around for so long, yet legions of new filmmakers and directors insist on camera moves with no motivation or justification. What Claude failed to mention, is unjustified camera moves not only slow the tempo of the picture, but the tempo of the production. Elaborate dolly shots can cause longer set-up and execution times.