The second job I worked at after college was full of people getting perferrential treatment, completely worthless people would get promoted because they were just on the right accounts at the right time, while people who worked their asses off, would stay in the same position for years. I was one of the latter, I was good at my job and did it well, so my immediate manager kept moving me to different accounts if I was getting to close to a promotion, so he wouldn't lose me in that position. Finally got fed up and left, it was a great job, but I knew I wouldn't move up in the company.
Although my friend from college worked there too, he was really good at his job, but he also had some great luck. Each account he was on, within 5-6 months after he was promoted, his immediate boss would quit for a new job, so he'd just be able to slide in that role and move up to the next rung on the ladder and now basically runs his own dept. and is still under 30.