I would disagree. I contend that those that put tremendous importance on high school assignments (ex: the overachievers) come out needing textbook style answer

I would disagree. I contend that those that put tremendous importance on high school assignments (ex: the overachievers) come out needing textbook style answers because a huge portion of the time, high school assignments and tests are of the "This is what it says in the textbook. The textbook is always right. Go find the sentence and repeat it here." type. Furthermore, I doubt you can judge someone's ability to find solutions to non-textbook style problems via their performance in high school due to the fact that those sorts of problems are rarely brought up in a high school context. Case in point: Multiple choice tests and essay questions based on your ability to cross reference the textbook. Anecdotal evidence: I coasted through high school and have no trouble arriving at potential solutions (and gauging chances of success) when I meet problems with no discernible textbook-style solution.