Once again, this test has been developed over around a hundred years by hundreds, if not thousands, of psychologists. Who are you to just come along and say it's all wrong? This test is grouping almost 7 billion people into SIXTEEN categories, what gives you the idea it's going to be 100% accurate at all? Psychology is inherently pseudoscience. There is NOTHING that can change that. The brain and conscience is probably the only truly chaotic system in the entire universe. We can't predict what it will do. This test is as good as we're going to get because it's been researched and developed for so long. A "which Pokemon are you" test was probably thought up in fifteen minutes.
Also, these tests are based off of what you USUALLY do. Who's really going to think a question of whether they always plan ahead or not completely literal? And being sober, tired, stoned, whatever, those all change your personality and/or perception temporarily. They affect ANY test you take.
Now I do no question the method that these tests use. If you say you like to plan ahead, that means you the kind of person that likes to plan ahead, and we can all one to the tally board for the planing ahead trait. The logic is seemless. It describes back the person you described in these tests.
However, I do question how valid it is. How does it take into account the fact that people are not oftern who they think they are? I'm sure there are some people out there who would like to think they are highly social and do there best to get out at every chance, but in truth they are a lot more shy then they think, and are your typical intravert. The fact that you do not have an outside perspective on this makes is some what bias towards something you wish you were, rather then something you are.
I think getting constantly very high percentages should be a good clue to this. Even the most social butterfly enjoys some time alone sometimes, and the only people who should be getting 100% in anything are fictional characters with no depth.