So are army promotions for enlisted people just a question of time in grade? Or is there more to it?
Time in grade is only a minimum requirement. There’s more.
Discussed on another thread:
For enlisted POW’s promotions are a matter of time & grade, for the most part.
For other active duty bucking for NCO you have to take the appropriate leadership courses & achieve a sufficiently high score in testing. Then you branch establishes a “cut-line” for your particular MOS based on all scores. Then the promotion board weighs “other considerations”.
POW’s get promoted along — I guess — because the assumption is that they didn’t have the opportunities to further their career while in captivity.