In Illinois the written test is only 15 questions. I studied the sample quesiotns (4 to 5 times)and read the booklet 3 x's and scored 13 out of 15. That's pass here.
If you do the same in your state, I'm sure you'll pass the written. How many times to review is determined by you. I did it till I could answer the questions (out of order) as fast as I could read the quesitons.
The only problem might be anxiety but that should be it.