According to Ex Astris, it was initially built for VOY's "Flashback" episode (retrofitting the E-B back to its original Excelsior configuration was "deemed impossible"). Then it was re-used in DS9's "For the Uniform" as the USS Malinche. Then used three more times as a background ship in DS9 ("By Inferno's Light", "Dr. Bashir, I Presume" and "Ties of Blood and Water". Finally, the last appearance was in DS9's "A Time to Stand" as the USS Frederickson.
So a total of 6 on-screen usages.
So a total of 6 on-screen usages.