Our meats do not need long to cook!!!
Remember, LOW and SLOW, doesn't mean longer.
Crock pot style cooker - OK, but only it making bone broth on low for 24-48 hours or if stewing the meats. The crock pot actually fluctuates in temps and short or shorter cooking times will yield a tougher chewy meat because of the heat fluctuations.
Short ribs - Roast or sear the short ribs and then put in crock pot for 12-18 hours on low. Watch your water level. If too high, you will end up with more of a stew.
Stew Meat - Sear on cook top, then put in crock pot like short ribs, add in the amount of water or liquids you want and put on low for 12-18 hours.