At a former employer of mine it was common practice to only grant the pay raises and other benefits associated with a promotion six months after the promotion was given. The official rationale was that management needed to know you were going to work out in the position. Not suprisingly in practice the vast majority of promotions were recinded 4-5 months after they were announced. They always managed to catch people slipping up SOMEHOW over that time.
It was an horrific system but jobs were so scarce in that area that no one quit. (Obviously it wasn't a union shop.) Finally things came to a head when my friend and cubicle mate was promoted to group leader. The poor guy was put on earth to do the kind of Quality Control work the job entailed. He loved his job and worked at least three times faster than everyone else. Better yet he was obsessive about being on time for everything never slacking off during work hours.
In a normal company he would have shot up the corporate ladder. In this case the management freaked when they couldn't trip him up after 5 months. They started increasing his workload by the day. To the point where he was doing five and a half peoples share of analysis. He was my good friend and had a kid and needed the raise so I'd stay late for the first week and would help him finish his work. Then suddenly everyone was banned from assisting one another in their work load.
They finally got what they wanted and he missed a deadline and had his promotion canceled. It was honestly the saddest sight I have ever seen in any workplace. He literally cried the entire day in his cube while still doing his work faster than any of the rest of us.