Are 12 grades too many?

Physically, most people's brains are not ready to quit school at the age you are in 8th or 9th grade. Literally, your brain is not developed to the point that your higher level cognitive thinking is where it should be to succeed in college. Formal schooling to at least age 16-18 is logical and a plethora of scientific studies back the theory that developmentally it is a very good idea to be in a setting where your higher order thinking is being challenged on a daily basis.