For the longest time, I thought that The Challengers was an NBC daytime show because our local NBC affiliate, WGAL, aired the show. (Although I don't recall at what time...could have been 12:30?)
I'm not sure why I thought this, because WTXF in Philly (Fox affiliate) aired the show.
I loved the show as well, as much of it as I was able to see as I was around 10 at the time. I learned a lot about current events from watching the show, and it was very well done.
EDIT: WGAL aired the show at 10:30am, right before TTTT at 11am. Other interesting shows on air at the time from the Feb 91 ratings book:
TJW 90, WLYH, 9:30am
Feud, WLYH (then CBS), 10:30am, and WHP, 12 noon (both half hours)
TTD 90, WHP 5pm (I don't remember this whatsoever, and WHP followed it with Hard Copy of all shows.)
$100K Pyramid, WLYH 7pm (against Wheel on WHP)
Feud, 7:30pm WHTM (nighttime run against J! on WHP, WHTM ran Feud here for a number of years)
This would have been around the time that WHTM was shuffling Trump Card and MG90 in and out of their noon slot as well, but this ratings book shows them running Wapner at noon.