Once you have optimized any page, your log files often tell you how people are finding that page. Not just what keywords they are searching for to get there.
If you discover that people are using specific keyword phrases that you had not originally thought of, it is in your best interest to further explore those keywords.
Hint: More and more, you will discover that there is huge value in knowing how to analyze your log files as opposed to ranking reports the traditional way.
Why is that? Traditional ranking reports may soon become less and less useful as the personalization of search grows in popularity.