For sure it works.
I did some flashing on a portrait platinum series I printed last year. in fact I got few shining on the skin and the background was to bright for me . THe flashing help me to get a creamy background and no shine on the face.
To flah the paper I use another UV lamp (I use to print with a vacuum printer and Blacklight) and I put the coated paper at 2 meters from the lamp and expose for 10sec to 1 minute dependig on the effect I am looking for.