The only way to know if your site needs to be re-optimized is to keep track of your rankings. Minor dips and burps in ranking are expected, so checking daily isn’t necessarily recommended. A sudden major drop, however, can signify that your competition has figured out optimization as well, or that perhaps an engine’s algorithm has changed.
An optimized site, if done properly, should keep well. “I’ve written content that has done well for years,” explains Lloyd-Martin. “With the spidering engines, the nice thing is that it’s always been about content.”