Memorization and closed book tests are important for some areas. When seconds are counting the ER doctor cannot go look up how to treat a heart attack. That doctor also needs to know now only how to treat the common heart attack, but how to recognize this isn't the common heart attack but the 1 in 10,000 not a heart attack but has exactly the same symptoms as a heart attack case and give it the correct treatment.

However most of us are not in that situation. It is better for us to just look up those details as we need them because it gives us more room to handle a broader variety of situations.