The initial acceleration of an aeroplane is slow and so uses up runway. If you start your run at right angles you can be doing say 10kt. as you line up, also start with no flap because you will accelerate better clean then pull flap- at lift off speed, then gain speed in ground effect before you start to climb. This process takes more skill but uses less distance but you would not let a low time pilot try to fly the plane out of this sort of tight spot. I am not being critical of the standard teaching method of short field but saying that with a bit more skill you can improve on it.