Fieldcraft exercises vary widely and each places emphasis on different aspects of how to survive and conduct yourself in the field. Many involve two teams being pitted against each other. You and your team might need to move quietly, avoiding detection as you sneak upon an 'enemy' installation. Sound easy? Think again. Speed might also be a big factor of your success. Do you risk exposing your position at the cost of achieving your objective more quickly? Decisions like these are challenging and need to be made 'on-the-fly'.
A massive advantage of fieldcraft exercises is that they force you to use your own initiative, sometimes affecting your teammates. What would happen if the commanders of your team ‘went down’? Would you take control?
If you have natural leadership qualities, they'll definitely show themselves here.