It seems, during the 1980s, there was a movement towards 3 man fronts. During the 1990s, there was a movement back towards 4 man fronts. And, during the 2000s, there was a return to 3 man fronts.
The preference is cyclical. This is just my own observation. Feel free to chime in if you think I'm wrong.
"Many of the greatest things man has achieved are not the result of consciously directed thought, and still less the product of a deliberately coordinated effort of many individuals, but of a process in which the individual plays a part which he can never fully understand." - Friedrich Hayek