We do this for reverse purposes on hang gliders when the air is laminar, you are about 20 feet too high for a hill top landing at about 15kts and don't fancy the overshoot.
We call it 'shaking it down' - you rattle the 'A' frame forward and back using about the same frequency and amplitude which you would apply to a stuck door.
The effect seems to degrade the performance but controllability is retained and a shorter landing achieved.
We don't have a clue why it works and have often discussed it.