I took the MBTI about a decade ago and came up ENTP. My only shock was that my I/E was so close to the line -- I think of myself as ridiculously extroverted with a side of obnoxion.

Nevertheless the only thing I've used from this knowledge is the understanding that I am a process-based person, not goal-based. I have always enjoyed figuring out the specifics that lead to more consistent results, figuring out the analogies that get a person to do something more intuitively. I've always been a good loser at games -- I learn which tactics I didn't have.

...except for chess. I cannot stand playing chess. It looks like a purely deductive game until you play against people that know what they're doing. Then you learn they aren't seeing the best approach but merely sorting known approaches to a situation. They're flipping flash cards in their heads, and the winner has a bigger stack of memorized flash cards.

Using personality testing to get an efficient team seems like guessing the playoff spots before the first game. Teams rise or fall based on how well they work together to tune out noise and survive events. You can tell me that a person is more goal-based or introverted by nature, but that won't tell me which factor has become that person's personal hang-up. A "feeling" person may have grown up hating the pain of having sensation and therefore makes bad decisions by taking a gut instinct and rejecting it. An introspective person may have become hung up on getting out of the shell, aced Toastmasters, and otherwise become a skilled presenter or sales person based on sheer rebellion.

Tests such as these tell me less about a person than a single round of a role-playing game. Who will be a snitch instead of a struggler? Who will be bossy and who will give in when that's a bad idea? Put on some character masks and show me your real person.