Even though it’s used quite extensively, I’ve never liked “the fewer clicks, the better” as a metric for good usability. Chasing that metric can easily result in an interface where every feature is within a click or two’s reach, but the thing is so crowded that users have trouble figuring out where to go. In Satisficing Lukas Mathis draws from psychology to explain why this metric doesn’t make much sense:

A great user interface is not one where each goal can be reached with the smallest number of clicks possible, or where the user has to pick from only a small number of choices at each step, but one where each individual click is as obvious as possible. If your users have a clear goal in mind, each level of the hierarchy should have one option that clearly satisfies their goal—or at least gets them closer to that goal. As long as users feel that they are getting closer to their goal with each step, they don’t mind drilling down into a deep hierarchy.

It’s also worth skimming the Wikipedia article on Satisficing for some further background on the theory.