Today, every unique body flight position is a category or discipline of skydiving. Each category has rules for competition that can be judged. To compete at the highest levels within each discipline requires training in the wind tunnel.
The luxury of indoor skydive training is it is more time efficient (no riding in the airplane to altitude, no need to pack parachutes). Teams are able to fly together for two minutes (this is the equivalent of two skydives. A skydive usually lasts for one minute). Step out of the tunnel, review their technique with a coach and step back into the tunnel. This controlled environment increases the learning curve dramatically!