Search Engine Optimization is an ongoing, ever-evolving process that will need to be re-evaluated and updated over time. Search engines have incorporated a wide range of undisclosed factors in their ranking algorithms to reduce the impact of link manipulation.
Google claims it ranks sites using more than 200 different algorithms. The three leading search engines: Google, Yahoo and Microsoft’s Bing Search, do not disclose the algorithms they use to rank pages and are continuously changing the factors that they use to deliver and place results.
Therefore, SEO is an ongoing process. The results of Search Engine Optimization efforts will vary, and will require and ongoing effort to be most effective.