Record time is too short
Shooting at full 4K resolution: 16GB CF card = ~10 minutes (similar to those achieved when working with film). Recording to a 320GB Red drive = 180 minutes @ 4K.
Many broadcast productions delivering at 1080p may choose to shoot half res 2K. Shooting 2K: 16GB CF card = ~40mins of HD footage and nearly 720minutes on a Red Drive.