My school teaches that if you are going to fall short, then get the flap back up. I learnt this first time I did a glide approach in the 172. Took flap as per normal in the 152, but fell short. My instructor explained that it "flies like a brick with full flap compared to the 152, so if you need to take some flap up to extend the glide on final, then do so."
This was also said by the ATO when I did the PPL test recently. High on base and final, side slip in. Afterwards we went over the forced landing leg lengths and heights. During this he also said "if you find yourself falling short, then clean the flap up to help extend the glide"
His reason was, you only have one shot in a real emergency to get it in the field, so do what ever it takes!
So some places are teaching it to students, like me
