According to the Paramount Studio Group web site, Stage 15 was used for Star Treks The Motion Picture, First Contact, and Insurrection.
It is not known what Stage 15 was utilized for in this feature.
This stage housed the Genesis Planet set .
Stage 15 contained the Enterprise bridge set during the production:
Photographic evidence  shows that nearly the entire stage was occupied by the bridge. It also shows the open door to the adjacent Stage 14, which was used for Engineering and the corridors.
Stage 15 contained some of Insurrection's most elaborate sets, including the Son'a Bridge  and the Injector/Collector aboard the Son'a weapon . The latter was a very expensive set constructed of steel beams and was heavily bluescreened.
For Nemesis, Stage 15 was the site of the Enterprise bridge, Admiral
Janeway's office, and the Jefferies Tube set . Additionally, once the sequences on the Enterprise bridge
were completed, the set was converted into the Romulan ship Valdor's bridge