Beginning with "The Good, the Bad and the Ugly", which originally ran for three hours, Leone's films had usually been cut (often quite considerably) for box-office release. Leone was very conscious of the length of "Once Upon a Time in the West" during filming, and subsequently commissioned Sergio Donati, who had worked on several of Leone's other films, to help him refine the screenplay, largely to curb the length of the film toward the end of production. Many of the film's most memorable lines of dialogue came from Donati, or from the film's English dialogue adapter, expatriate American actor Mickey Knox.