I believe that success as an audio engineer can be measured in how dynamic you are, and in how well you have accomplished the task asked of you. For example, if one client is looking for a crisp, clean voice recording (e.g. for an audiobook or a podcast), and another client is looking for a grungy, distorted drum set recording (like on a rock record), being able to accomplish both of those things is incredibly important. Often, an audio engineers work is being taken and manipulated further in post-production, but getting 90+% of the way to the sound the client is looking for is the true mark of success for an audio engineer.