One of the few good things about having a bad memory is being able to reread books. While I obviously remember the high points, main events, and the overall plot, I forget small details or more minor occurrences and so it's not as repetitive to reread books as it could be if I had a better memory.
It's funny how this book answers questions while raising others. Once again I feel much appreciation for Neville and the Weasley twins as relatively minor characters who are among my favorites. And I so wish I had the memory and smarts of Hermione, I would have loved to have a friend like that in school!