There are certainly situations where someone is seen as a "hotshot" in some regard and a company goes out of its way to give him exposure/experience/training that will permit them to rapidly position him where they think they want him. Of course that sometimes backfires when he takes that experience and walks out the door to a competitor... or when her turns out not to have been the genius they thought he was. But it's debatable whether that's favoritism as the term is usually defined.
There are also people who simply work particularly well together, and a manager who sees that happening would be foolish not to take advantage of it. But again, it's unclear that's "favoritism".
Outside of those -- and even including that -- I would say that there are few, if any, GOOD management strategies which employ favoritism in the sense of favoring someone for reasons that are unrelated to the business. That may not keep people from confusing personal reasons with business reasons, or from lying to themselves about their reasons, or from simply doing something stupid.
On the other hand, if you're on the losing end of the decision, it's entirely too easy to see something as favoritism when it may actually be justified. Going back to my first paragraph, I've seen someone fast-tracked in a way that I think did some harm to the groups s/he was involved with, but I honestly don't know all the motivations, or whether the net result to the company as a whole was positive or negative; some of the repercussions are still settling out many years later. I have an unsupported opinion, but that's all it is... and s/he did do some sterling work along the way.