I did it in the normal timed format but anytime I came across something I was not sure about I jotted it down on a piece of paper (not a long sentence, just a note to jog my memory).
Then after submitting and getting a score I went back and used google, FA, and Rapid Review to look stuff up.
It should take max 4 hours, I didn't have the patience for 16 hrs. I used it as a gauge of where I am, not as a learning tool.