My process is slightly different...
Normal running:
Left Dial on Auto,
Centre Dial on 22-23 degress, Fresh-air,
Right Dial: Aircon On and Auto.
Moist mornings (when the engine is cold and things look like they might get steamy):
Check centre Dial is still Fresh-air (it does seem to reset itself occasionally)
Check Right-dial still Aircon On andAuto
Left dial, Switch on Heated Screen/Mirrors and crank dial all the way round to Screen.
This clears the fron screen within quarter of a mile, then I rever left-dail to Auto. Rear screen clears within 1-2 miles.
Cheers,
JohnK