Some soldiers got to come home permanently if they completed a certain number of missions. In particular, early in the war if a USAAF person completed 25 missions they got to come home. The catch is most did not survive 10 missions let alone 25. When fighter escorts became possible, the total number of missions was raised to 50 as they became safer.
The ground troops would get Rest and Recreation at some R+R center in the area. They did not get to come home as the only practical means of going back and forth was by ship. It would take your entire leave just getting home and back, Most understood that once you got deployed you were gone for the duration of the war. That gave everyone added incentive to get the war over. The problem with Vietnam and the current wars is the incentive is to just stay alive until you get home. If you know you are going home in a month, why stick your neck out to win the war?