This means that you, in turn, must evaluate the quality of the evaluators themselves. Fortunately, as time progresses, subject trees are developing their own reputations for quality. If you're looking for some obscure, fringe thinking type of topic, the experts who created the directory may have weeded those pages out. Thus, the non-evaluative search engines might be a better strategy. Because human intervention is needed in order to get a page listed in the directory, the most recently published pages are never found in the directory.
Subject trees are often several months behind the publication schedule.
If you stop to think about it, that's not that much different than traditional libraries who often have cataloging backlogs. The use of subject trees is pretty much intuitive, so I won't get into a big explanation here. All you need to do is click on the links that interest you. Depending upon the nature of your information needs, this strategy might be your first choice, or you might fall back on it when a keyword search has not met your needs. There is quite an assortment of Subject Trees available, both general and specialized, and you'll keep running across more as you go.