To be promoted to E5 or E6 in the military (the army at least), the soldier will appear before a board of senior enlisted soldiers. He (or she) will be required to answer a number of questions about their job specialty, leadership issues, ethical dilemmas and a number of other areas. The board will consider the “interview” performance as well as their “resume” which will include military schools, awards earned, college courses completed, performance on physical tests and whatnot. All of this will be considered when they decide whether or not to promote them.
To make E7, E8 or E9, soldiers do not appear in person before a board, but rather compete across the entire military by submitting their “packets” that highlight all of their credentials. They must have good evaluation reports, must have held key leadership positions as well as all the areas mentioned for the junior soldiers to do well. As leaders rise in rank, they must also complete mandatory military schooling appropriate for their rank/position if they want to progress further.
For officers it works a little differently. They do not appear before a board but rather their credentials are reviewed periodically by a national board. There is generally a minimum amount of time associated with receiving each promotion as well.
I hope this helps…