I used the ASA Test Prep books as part of my preparation and found them very useful - they have a short section covering the topic followed by relevant questions.
Whilst it seems very popular to criticise the use of question banks, I have never taken a single academic exam where the use of past-papers wasn't an accepted part of the exam preparation. If you were to just learn the subjects without ever having looked at the types of questions to be asked even the best prepared would struggle. Personally I find that studying the material then answering questions is the most effective way of learning the topic.
As others have pointed out, under the FAA system if you don't know the subject then you will get caught out by the examiner during the oral test.