Back-to-back filming is the practice of shooting two or more films as one production, thus reducing costs and time.
Trilogies are common in the film industry, particularly in the science fiction, fantasy, action, horror, thriller, and adventure genres. Production companies may choose, if the first film is a financial success, to green-light a second and a third film at the same time and film them back-to-back. In a case where a lengthy novel is split into multiple installments for its film adaptation, those installments will usually be filmed back-to-back.