Some people say we cannot manage what we cannot measure. I say we cannot solve what we cannot see, or at least visualize somehow.
Projects are problem-solving exercises. The entire project is one big problem. We might be building a new product; that's a problem to solve. Or we might be trying to create something well understood but within a challenging amount of time, to a tight budget, and demanding specification. Or we could be moving our organization forward through a change initiative. These are familiar project environments that are puzzles or problems to solve.
Then within this large problem environments, we have hundreds of everyday challenges to answer, too. "How are we going to manage without the installer today?" or "The pilot group has requested 400 changes, now what do we do?"