> In the US system ... everyone else is promoted and then assigned
It's worth pointing out that one of the reasons this system works in the US army is that non-commissioned officers are trusted with a great deal more responsibility than their Soviet counterparts were. The mechanical promotion of junior officers would be impossible without 15 year veteran NCOs taking care of a lot of the grunt work that Soviet officers got stuck with, simply because the system wouldn't trust NCOs with it.
It's worth pointing out that one of the reasons this system works in the US army is that non-commissioned officers are trusted with a great deal more responsibility than their Soviet counterparts were. The mechanical promotion of junior officers would be impossible without 15 year veteran NCOs taking care of a lot of the grunt work that Soviet officers got stuck with, simply because the system wouldn't trust NCOs with it.