Comment by parsimo2010

There are schools that use placement exams to place new students into their first course level, partly because there is inconsistency between grades from different high-schools, and even standardized test scores aren't amazing predictors of college course performance (they are correlated, just not as much as we'd like). The school I teach at does this, and we often place students who got as high as a 4 on their AP Calc AB exam back into introductory calculus to take again.

GP seemed to be talking more about a qualifying exam at the beginning of every course. I don't think that will ever happen mostly because of what you stated as, "the graduation delays that remediation adds." Can you imagine how long it would take average students to graduate, or the dropout rate, if we made each student pass a placement exam before every course? We couldn't implement this without a radical change to how universities work.