The U.S. Army has discovered that since September 11, 2001, the number of older recruits (over 30 years of age) has increased 92 percent. While these men (and some women) had a harder time with the physical demands of recruit training, they were much appreciated for the additional maturity and life-experience they brought with them. This phenomenon, of the "steadier and more reliable older soldier" was noted when conscription was introduced during World War II. The older draftees, even though they were much less enthusiastic about being there, were more reliable and productive than the younger volunteers. This was one aspect of the draft that career NCOs and officers knew they would miss when the army went all-volunteer in the early 1970s.
While the older recruits don't have the military experience of NCOs, they do have a lot of the maturity. This makes a unit more stable, predictable and productive. Reserve units have long been noted for these characteristics. On the down side, older troops who are married, tend to be more likely to develop combat fatigue. The reserves also had health problems with the many, much older (over 50) troops, who were prone to more illness when in a combat zone. But 30 year old troops right out of Basic Training, are just the kind of troops officers and NCOs like to have, and since September 11, 2001, there have been thousands more of them.