How do you measure it? Both giving different incentives to different members of the team and giving random incentives every time will probably DEMOTIVATE people for obvious reasons (it will feel "unfair", "unpredictable", "random")
I guess a valuable scientific study would try to see the delta between what people like and what they think they want. Applying that in real teams though, has a lot more to do with the personal experience and ability to deal with peoples and teams. Some understanding of one own personality and psychology sure helps for getting that kind of ability.
