if your website gets penalized, it would not be in the the search index
if your website gets an over optimized penalty for a keyword, causing you to lose rank for that keyword, then you need more inlinks using other keywords to dillute the over optimization penalty.
Some people fall into the trap. They see their ranks fall for a keyword and add tons of links using that same keyword to try and save it...but, they actually make it worse. Now you know better.
Never stop building inlinks. Use 5 or 6 keywords per site to avoid such penalties. IMHO
~Ray