Complex sentence: Stage productions continued to use the original placing until Richard O'Brien revised the script for the 1990 West End revival in which he returned the song to the film's placing for reasons of pacing, most productions now follow this order.
Split into simpler sentences: Stage productions continued to use the original placing until Richard O'Brien revised the script for the 1990 West End revival in which he returned the song to the film's placing. For reasons of pacing, most productions now follow this order.