Several years ago, my Mom read aloud Fanny Crosby’s autobiography to Caroline and I. I was struck by how much of the Bible she had memorized. She knew the Pentateuch, the Gospels, Proverbs, Song of Solomon, and many of the psalms by heart. She often memorized five chapters a week. Wow! Hence, I always smirked when people told me I could memorize Bible verses quickly!
You see, I can memorize about a verse a day. I do it as I exercise on the treadmill. The problem is, if you were to ask me to repeat what I memorized a year later, it would be completely gone. I might be able to stammer through some of the verses, but not a lot of them. I memorize by chapter or book. I repeat the verses over and over again. But, if I don’t recite it constantly, even while I’m memorizing something else, I’ll forget it. So, every once in a while, I come back to that passage and recite it; sometimes I’ll have Caroline listen and stop me if I miss a word. And, yes, I memorize word-perfect. Otherwise, I wouldn’t be as confident when I want to use that verse.
A lot of people ask, “Why all the trouble?” Here’s why: “I have hidden your word in my heart that I might not sin against you.” Psalm 119:11
For a more in-depth reasoning, I would recommend this great post by John Piper. http://www.desiringgod.org/resource-library/taste-see-articles/why-memorize-scripture