I trained many military students in the simulated art of zero/zero take offs from the ground. I could never really see the point unless you were being shot at or had some other kind of extreme emergency. The risk simply outweighed the reward, especially if you were unfamiliar with the climb out path. Very few students showed much inability to complete the maneuver though - but I don't think this is a path that civilian operators should be encouraged to pursue or we may be educating our 'masters' into a new realm of confidence and expectancy. The old world methods of aviating, utilizing true refined ability with fine finesse have been overtaken by touch screens and button pushing.