we are not doing it, as here on bussiest airports it is not even permitted to set take off flaps before taxing, not to injure somebody from ground stuff moving arround aircraft during/after pushing back. Then having a precipitation of any kind during freezing conditions, we are allowing it to reach the flap areas, which would normally remain hidden. If doing it after deiceing completed, just having a clean concept achieved, by letting untreated areas exposed to precipitation, it will become iced and than we would have to go back for deiceing...this is why four european airlines I was flying for, had omitted this test, except in cold weather, below 0°C and no moisture, surfice accumulation or precipitation present, at remote airports on pilots discretion...which in fact meant seldom or never, with the accent on never
