Yes,but; there are always exceptions. One made MG.
My favorite mustang made it to 4 stars and Chairman of the Joint Chiefs of Staff, General John W. Vessey, Jr.. His military career lasted from 1939 to 1985. He began his career in the Minnesota National Guard and received a battlefield commission during the battle of Anzio in World War II. General Vessey also served in Korea and in Vietnam. He graduated from college at the age of 41 and also attended the Army helicopter school.
In 1982, President Ronald Reagan appointed him as Chairman of the Joint Chiefs of Staff.... http://en.wikipedia.org/wiki/John_W._Vessey_Jr.