Complex sentence: Most of the syndicated programs were "nighttime" adaptations of network daytime game shows; these game shows originally aired once a week, but by the late 1970s and early 1980s most of the games had transitioned to five days a week.
Split into simpler sentences: Most of the syndicated programs were "nighttime" adaptations of network daytime game shows. These game shows originally aired once a week, but by the late 1970s and early 1980s most of the games had transitioned to five days a week.