Strengthen with Sufficient and Necessary Principles Ex 8-9

While I was working through these two examples myself, I did not notice the changed questions stems, so I did not use either Necessary or Sufficient Premise techniques to solve them. Yet, I got both answers correct and now have a few questions. How common are these specific Principle questions that use either Sufficient or Necessary Assumptions to strengthen, compared to regular Principle Strengthen Questions that do not invoke Sufficient or Necessary Premises? For these Principle Strengthen w/ Sufficient or Necessary Premise Questions, is one able to use regular Principle Strengthen techniques to find the correct answer choice (like I did for Ex 8 and 9), or will the LSAT try and trick students by giving multiple answer choices that strengthen the argument, but only one that does so with a "Sufficient Principle" or a "Necessary Principle," like how Strengthen w/ Sufficient or Necessary Premise Questions sometimes presents an answer that does indeed strengthen the argument but is not a sufficient/necessary assumption?