I remember reading a letter that was written by Paramahansa Yogananda and in it he wrote. “Do not look at the beggar on the street and say, ‘There but for the grace of God go I’ because he may be in his last incarnation and you may have many more to go.” So once you have memorized a sutra if you do not live the words within it what good is it? The value is not in the memorization, but in the application! Buddhism is NOT about metaphysics. It could be considered a guide to being kind to yourself and to others…the universal Golden Rule.
It is also important to remember the words of Siddhartha Gautama (The Buddha) when he is quoted as saying,
Do not believe in anything simply because you have heard it.
Do not believe in anything simply because it is spoken and rumored by many.
Do not believe in anything because it is found written in your religious books.
Do not believe in anything merely on the authority of your teachers and elders.
Do not believe in traditions because they have been handed down for many generations.
But after observation and analysis, when you find anything that agrees with reason
and is conducive to the good and benefit of one and all, then accept it and live up to it.
Enlightenment does not come “from” the sutras but from living a life as illustrated in them—to do that more easily and more often we need to put some of them to memory. That way we have the principles anchored in our unconscious as well as our conscious mind and the words can be of great help to us especially in times of challenge.