I never memorized things for open book exams. I did, however, know my outlines backwards and forwards, I had it highlighted and tabbed, and always had plenty of time to use it. And I did very well.
That said, a very short, one page list/checklist with main/basic elements of negligence, intentional torts, and defenses may help speed the process of issue spotting up, and help prevent missing issues because the applicable rule didn't automatically pop into your head.