re: Takes time, and money . . .
Rising up through the ranks requires board presentations and skills evaluation. Those receiving the presentations and evaluating the skills have already risen through the ranks. These are the people who choose who gets promoted, and who does not, and the procedure is set up to be as impersonal a process as possible.
To get inside the mind of the promotable soldier/noncom/officer would require unimaginably expensive federal investigations, as there are literally hundreds, sometimes thousands of military promotions every month.
Dan