Lizzy,
One of the major points of the xiggi method is to use ONLY CB SAT tests for practice, the ones on the website are NOT official CB tests. Perhaps that's why they're less confusing to you. It's not very helpful to practice with different tests than what you'll be taking for a real score, it may mislead you into expecting a higher score than you will actually receive.
Even if you don't use xiggi's methodology (everyone has to find the method that works for them), I would always recommend using only CB tests (either SATs in the blue book or PSATs ordered from the CB) as any other tests (including Kaplan,
PR, etc.) are never going to be exactly like the ones you'll be sitting when you take the SAT for real.