if you are a mile out on final and realise you have put down more flap than you need what is the problem with raising a notch? You should have plenty of time to ensure that you raise the flap and not the gear and avoid dragging the aircraft in for an excessive period. If you refuse to raise the flap and you engine quits you are not going to make the runway which would be a bit daft.
As for raising the flap just before landing it is never anything I have done but I can see how in capable hands it might have its place, for the average ppl though it has not. I have operated a standard (160hp) 172 in and out of 300m and never found any real difference with raising the flaps in the landing roll (the book procedure for shortfield) and not. They were electric though so they spent most of their time going through the t/o setting and therefore lightening the load on the wheels and defeating the object.
Of course if you did raise the flap prior to landing to shorten the role and got it a bit wrong and ended up with damaged gear/wing spar as a result then the insurance man might not be too sympathetic.