When I served in the US army a trainee could complete Basic, Advanced Individual Training, and then go to OCS or Warrant Officer school. At OCS they got E5 pay, which is sergeant. Warrant officers flew helicopters.
An option was "Instant NCO School" from which a graduate achieved sergeant (E5), and the top 10% achieved staff sergeant (E6). While attending this school, you were paid E4 pay.
I think it is still about the same.
I have a bit of a bone with this. When I went through the Q-Course, we had guys who also started but were brand new to the Army. Basic/AIT/Jump School/Q-Course = Instant NCO.
They were some of the worst leaders I ever saw. Whining cry-baby's who thought they knew it all and weren't afraid to tell you that, but when it came time to perform, they sucked.
They had no leadership skills, no tact, and they didn't know their way around the Army system. Yet, there they were, and they were expected to be the experts.
With officers, it is expected that the NCO's take that new Lt. under wing and train him/her. How can that happen when the NCO doesn't know his fourth-point-of-contact from a hole in the ground?
Another bone I have is the comment Dex made above. Why was someone fresh out of Basic, who was receiving E-5 pay by virtue of OCS, be promoted to Sergeant and permitted to train troops? Again, a leadership issue.