If you noticed over the last couple of years, the ABC O&Os don't carry World News Now anymore, or if they do, it's probably thirty minutes to a hour at most; if you want to watch World News Now in an ABC O&O city, you have to watch it on ABC News Live, starting at 2am ET. Instead now, the post-Nightline slots are occupied by replays of the 11pm (10pm CT) news, and reruns of Kelly & Ryan and Tamron Hall.
Almost the same thing with CBS and its overnight news programming; the CBS O&Os at least over the last ten years or so would always air a truncated version of Up To The Minute/Overnight News around 3:35am local time, while most of the other affiliates would start airing the overnight news starting around 2 or 2:30 local time, depending on the market.