The more test questions I answer the more I start believing that you just have to know everything. I think it's 95% knowledge (if you have it), 5% basic application of the knowledge. Sure, critical thinking is nice, but it's very tricky and can easily lead you to a wrong conclusion... And in many situations logic will be helpless... If the question asks you about when to administer food with gastrostomy tube... what will you think? Wait for decompression, or is the stomach supposed to be decompressed already (NPO client, suction), should you wait for incision to heal, or is it safe to pump food into stomach which has a fresh incision... should the food be warm, cool, small portions, medium, should it contain carbs, fats, proteins? should it be administered every 15 min, or every hour, or every 4 hours? How are going to figure all of it out without any knowledge using only common sense?
I don't know how about you, but my intuition (which is always a part of critical thinking) is most of the time fails me when I have to chose between two possible answers. If I feel the answer is right - it turns out to be wrong, if I try to pick the other answer because I know my intuition is wrong - I'm still wrong. When you know the fact - it's a single truth and you have no doubts. When you don't know the fact, and try to critically think, you may come to 100 possible explanations of the problem all of which seem real and reasonable... or all be wrong because you base them on faulty educated guesses rather then solid knowledge, and/or looking in a totally wrong direction than question asks.
For example, a question (From learningext) gives you 4 women in birth, and provides information only on their labor status (station, dilation, contraction duration...) and asks you whom you will attend first. Of course you might think, the one who has the baby at +2 station, full dilation and strong contractions because she's about to give birth and needs more frequent monitoring of her and baby status. But the correct answer is that you should choose the woman with the highest station (-1) and narrowest dilation because she's about to break water (or just has broken), which poses a danger of fetal umbilical cord prolapse. It's absolutely logical and at the same time totally insane. If you had similar question you will know how to answer it, but if you didn't (don't have knowledge) - I have no idea what in the question wording could possibly lead you to the conclusion stated in the rationale. I don't think even Einstein would figure it out.
So I think knowing the material is essential. Strategies are nice as an occasional substitute, but material is what one needs.