Once the initial search engine optimization process is complete they keywords should be monitored around twice a month. As any one ranking report is only a window in time, ranking reports should be looked collectively over an established period of time. If your site has never gone under optimization before then, depending on your back links and the competitiveness of your keywords you may see drastic improvements. After this initial phase it is perfectly normal and expected to see fluctuations in keyword rankings as search engine rankings are never static.

Search engines are continuously adding new content, discovering new links and tweaking their scoring algorithms. Because rankings can fluctuation in any given day its important to look at the ranking reports over a period of time to observe true trends. Just because you have noticed a keyword has declined in Google the last two ranking reports may not mean that you need to take drastic actions and re-optimize or overhaul a page. If you are able to look at the ranking reports since the baseline (initial pre-SEO) report and see an overall upward trend, then you may want to wait until a third ranking report. As a rule of thumb I like to see three declines for a keyword before considering taking action, unless the previous two declines have been drastic.

As the program progresses you will inevitably have rankings that form a declining trend. When this happens you may want to consider if your linking program has been targeting the keyword(s) in question in addition to examining back links and on-page optimization of sites that now rank higher than yours.