I was thinking about relationships and Rallying.

In rallying you have a driver and a navigator. Each of them are crucial for the success of the team.

Now, if we think about relationships you can get:
A driver and a navigator - ideal
two drivers - where you have the second driver instructing the first about how to drive the car instead of watching the map
two navigators - I'm not sure what might happen here but for sure the one at the wheel is not driving the car as well as he could
and a navigator in the driver seat with a driver in the navigator seat - same scenario as with two drivers only a little bit worst because the navigator driving would have to handle both his poor driving skills and the constant nagging of the driver in the navigator seat.

Is this metaphor valid for betas only?
Is the driver the extrovert or the sensor? I think it is the sensor.

What do you think?