Also, don't worry too much about "efficiency." Some people will ponder for hours whether the computer will execute CASE vs. IFs "faster" in this situation or that one.
Don't worry about that. Worry instead about clarity. Soon enough someone will be looking at that code again, to debug it or to extend it in some way. Write for that person. Also be conscious about how easy your code will be to maintain. Those are the considerations that really matter... For instance, CASE might be much more tolerant of a typo, vs. a misplaced part of a nested IF...