Hi bgbeidas,
It's not clear what you mean when you say 'make the official guide questions my number 1 practice resource...' Any of the recent OGs should be a part of your overall study plan, but pinning your hopes of a high GMAT score to whether you work through a particular book or not isn't realistic.
The GMAT is NOT a test of your memory - it's a test of your critical thinking skills. Yes, you will work through lots of practice questions, learn/practice skills, etc. and you will (hopefully) remember your training when you're answering Test Day questions, but honing your skills on "non-hard" questions is what's essential to properly dealing with more difficult material later. If you're looking for harder practice problems, then that's fine (and there are enough sources to be had), but this is all meant to say that you don't actually have to practice a lot of harder questions to score at a high level on Test Day.
GMAT assassins aren't born, they're made,
Rich