I just viewed the test as an indicator (as I do most tests). I was a bit surprised at how high my secondary language scored (didn't really realize I had one), but as I put much more thought into it, it made sense. SourGirl is right in that the test should not be taken as absolute, your love language can change and evolve over time and from relationship to relationship. My top three tend to rotate order of importance.
I found the book EXTREMELY helpful, especially as we went over it together. It's so much easier to say to my husband, "Hey, I need some quality time" or to make sure that I express my gratitude when he cleans up the kitchen. It gave the both of us a lot of insight into each other.