When does the new list of critically short MOSes in the BEAR program change and get posted? Is it usually 4 times a year or is it very fluid and adapts month to month?

It'll be posted once DA/HRC get the go ahead for new MOS levels.

AR is there any time frame like once a quarter that that may happen?

Hopefully no more retreads into the Signal Corps. Our points have been successfully jacked up from way too many retreads getting into the Signal Corps, shoplifting a position into a REMF unit, then bailing out once they gotten some paper (certs, degrees) hosing points for the career soldiers. Please excuse the rant. Been too long for my highspeed SPC/SGT's aren't getting promoted.