Just spit-ballin' off the top of my head, since it's 2am. Others can chime in with more concrete facts.
Honestly, it's probably just easier to figure out when stations have had broadcasts in the 4pm hour, period. WMAQ, for example, flip-flopped between 4 and 4:30 for most of this century before expanding to the full hour in 2016. WBBM, on the other hand, was fairly consistent with a 4:30 newscast, abandoning the hour entirely in like 2004 or so. Both stations maintained 4:30 shows through the 90's, instead ditching 6pm newscasts for a time, as syndicated fare gave them a more competitive alternative to the juggernaut entry on WLS. Whenever both were absent from 4pm in the early 2000's, WLS would tout their exclusivity in their open. WGN entered the race in like 2014, and WFLD just this year. All 4 stations air an hour at 4, with WBBM being the only holdout, but Judge Judy (even if they continue with reruns next year) surely rates better than if they did news.