Depending on how your particular VE team prepares its tests, there are potentially a near infinite number of exams.The Extra pool is quite large , something over 700 questions, deliberately to keep anyone from just learning the test. The point being, you just need to KNOW the material,as opposed to just learning the test.
Some people prefer to use the practice tests on www.aa9pw.com
, which allow you to focus on particular parts of the pool that you're having trouble with.I found the Gordon West books very helpful for all 4 tests that I took, but that's been a few years ago.
Take your time. You'll get there.Understanding the testing process , and using that to your advantage is OK , but there's no substitute for understanding the material. Good luck on your upgrade.