What none of these tests, contest or not, can filter for is long term work ethic, dedication and creativity. Of course, these may not be important for all jobs. It is easy for some personality tyles to get excited and focused in the context of an event. It is a very different story to dedicate yourself intensely to a project or a codebase for years. I know people who suck at tests who blow away just about anyone due to the intense dedication to the job they can deliver on a consistent basis.