As far as I know, there is not a lot of research that was ever conducted on the decompression model. Way back in 2002, which I think was the very first time this model was used with individuals coming back from Afghanistan, it was done in Guam at the time. There was one study being quoted, which looked at the difference between U.K. soldiers coming back either by plane or by boat. Those coming back by boat--it took longer--seemed to show better adaptation, I would say. I will not cite any mental health statistics at this point.
There has been very little research. It was mostly a leadership initiative, and it's also logic. If you are in combat and you pack your bag and 24 hours later you're back in your front room with the children running around you, it can be very quick in terms of travel. It is good common sense to have a time to rest--rest is a big one--and to recover.