Following analogies are according to my understanding on status of Quran, Sunnah and Ahadith:

Suppose we have a text book on a particular subject. The book claims that it is complete and the last book on the subject. There is instructor who teaches this book and also gives solved examples of the questions in this book. The best instructor will teach how to answer the question by giving at least one example for every sort of question. The teacher is in direct contact with the Author so he understands the book best. Author has made it the responsibility of the teacher to transfer this book in the best way to his pupils. The teacher does his duty very well. Author has also told the teacher the way in which He wants pupil to practically follow the instructions in this book.
Now the students who follow the text, instructions of the teacher and examples done by teacher will get the best grade.
On the other hand there is a student who skips the class, ignores the instructions and reads the book himself. He may think that the book claims to be complete so I do not need instructor. He will make his own understanding of how to solve the questions. What are the chances of this student succeeding in the test? May be he has better knowledge of all the text in the book but does he know how to apply it practically? Does he know how to start answer of a particular question and how to end it? Does he know how much content is enough to satisfy the requirement of the question?

If anyone is wondering what I am talking about then:

Text Book is Quran.

Subject is Way of Life according to wish of Creator.

Author is Allah.

Instructor is Prophet Muhammad.

Instructions are Sunnah.

Solved Examples are Ahadith.

The teacher has special well established instructions on the practical way of solving the question. ALL THE students of the senior class transfer these instructions to ALL THE students in the new class effectively. They do not do this in isolation but with the consent of all the other students. (Sunnah)



Some students may even take the notes from the class and transfer these to the students who are absent. The students have tried their best to note everything exactly as they understand. But they may have missed or misunderstood a few things. But still they do have useful information with them. Acknowledging their work is not rejecting the claim of the book that it is complete book on the subject. Some of the students also approached the teacher on the matter which they did not understand themselves and noted down in their memories or on paper the explanation. This explanation is ACCORDING TO the text. This may be specific to the student who asked the question.
(Ahadith compilations)