At cambridge we have a good long runway, I still ensure that my students can land in the minimum distance possible. We have shorter grass strips avaiable to assist with this technique.
However, on PFL training you select an aiming point 1/3 of the way in the field and use flap (and side slip but not in C152s) to bring the aiming point nearer the start of the field.
I have found that some students add 5 knots on the approach speed for mum, and then maybe another 5 knots because it is windy. This means they will never pull of a short landing. Before you know it you will be touching down at 90 knots!!