Sorry, I'm not a golf instructor. This is just my two bits as a teacher, but teaching is teaching.
A lot of factors play into these questions. How well was the information delivered; how well was the information received; how much practice was involved. Also, what is an acceptable level of mastery? The best teaching practices allow for a series of steps -- I show, we do, you do, you teach. The theory is that one can not truly master something until they can teach it as well.
Of course with golf more factors come in as well, such as natural ability and practice time. I'd say to ensure the greatest possible chance for success that golf instructors, just as teachers, need to determine an acceptable level of mastery and then teach to it before the student leaves. The idea here is that no student does homework on anything that they are still struggling to learn because it can introduce too many possible missteps and bad habits along the way. Homework, just as practice, is best utilized when the skill is already learned.