I have an idea that they are not to be used below 200'.
That was certainly true when I was involved in DCA flight testing of radio navigation and visual aids many years ago. Below 200 feet was the cut-off height for T-VASIS certainly but I am not sure about PAPI because it was not operational then in Australia. In any case, if the aircraft is using either of the two visual slope aids it is assumed that the approach is already stabilised by 500 feet and by 200 feet the angle should not have changed measurably. However if the ILS glide path is available it is far better to stay on that glide slope until close to the flare because of the limitations of visual approach slope systems and their siting to the side of the runway.