Late Night helped launch the career of host David Letterman, and influence later entries into the genre. Despite Carson's endorsement of Letterman as a successor following his 1992 retirement, NBC chose Jay Leno instead, and Letterman departed for CBS to host the Late Show as a competitor beginning in the 1993–94 season. Late Night would continue as a franchise with hosts such as Conan O'Brien and Jimmy Fallon—both of whom would later go on to host The Tonight Show (albeit briefly in the case of Conan). The same season, Fox scheduled The X-Files as a lead-out for its sci-fi western The Adventures of Brisco County Jr., with the expectation that Brisco County Jr. would serve as the anchor of its Friday-night lineup. However, The X-Files proved to be significantly more successful, and would eventually run for nine seasons. By contrast, viewership for Brisco County Jr. declined throughout the season, and the show was cancelled. Fox attempted to use other sci-fi shows as a lead-in for The X-Files (such as Sliders and VR.5), but they were similarly unsuccessful. A weak lead-in can have an impact on the viewership of programs that follow; NBC's 2009 attempt to strip the talk show The Jay Leno Show (a spiritual successor to Leno's tenure of The Tonight Show after Conan O'Brien succeeded him) in a 10:00 p.m. ET/PT timeslot proved detrimental to the viewership of late local newscasts on its affiliates. Blocks Block programming is the practice of scheduling a group of complementary programs together. Blocks are typically built around specific genres (i.e. a block focusing specifically on sitcoms), target audiences, or other factors, with their programming often promoted collectively under blanket titles (such as ABC's "TGIF" lineup and NBC's "Must See TV"). Bridging Bridging is the practice of discouraging the audience from changing channels during the "junctions" between specific programs. This can be done, primarily, by airing promos for the next program near the end of the preceding program, such as during its credits, or reducing the length of the junction between two programs as much as possible (hot switching). The host of the next program may similarly make a brief appearance near the end of the preceding program (sometimes interacting directly with the host) to provide a preview; in news broadcasting, this is typically referred to as a "throw" or "toss". A bridge was used by ABC between Roseanne and the December 1992