There is actually a school of educational thought that advocates what is called standards-based grading, which is supposed to base grades only on mastery of learning standards. Teachers can select the means of documenting mastery, including test repair (repeat testing until a minimum standard is reached). Where I work, our official homework policy is that homework cannot subtract from your grade, but it can add to it. (Granted, this does not entirely prevent certain faculty from sneaking higher weightings for disguised homework into the syllabus, or from using low responsibility grades as an excuse to downgrade placement recommendations for the subsequent class.)

...pronounced like the long vowel and first letter of the alphabet...