R elying solely on search engines to find what you're looking for is insufficient for the following reasons. There's an average lead time of 6 weeks between submission of a site to getting it indexed on a search engine. Search engines are all different. So the effectiveness and efficiency depend on which one you use. Searching is an art.
Some search engines follow boolean logic expressions.
Not all submitted sites get indexed. This depends on the meta tag descriptions and keywords as well as the words on the site itself.