Originally Posted by strelnik

I hope it is not a surprise to anyone, but the military personnel system weeds people out at certain leve;ls.
On the enlisted side: E-5, E-7, E-8 for various levels of skill and thinking capability.
Ditto with the officer and warrant officer corps:

Many captains never make major, many majors never make lieutenant colonel, many LTCs NEVER make O-6 bird colonel.

It's for a reason: they are not up to the task.

Many warrants never make CW3 for that reason.
CW5 is a different story: some senior CW4s don't participate for CW5, because it means leaving the technical specialty you have done all your life to become a full-time paper-stamper for very little money and less respect.