This was very interesting.
Seeing this, and with what I remember to be the history of what aired when and on what channel in the Philadelphia market, I have to wonder if many of these timeslots have more to do with history and an "if it ain't broke, don't fix it" attitude at the local level.
In Philadelphia, Wheel/J! have always been on WPVI. Originally J! was at 4pm and Wheel at 730pm (you'll see my theory as to why coming).
In the mid-70s, The PA Lottery would air at 7pm, and the Muppet Show (great companion to the lottery) would come on at 701pm. At 730 there would be a game show. IIRC, Joker's Wild was there first (and I say first from the time in maybe 1976 when the Muppet Show first came and I started watching it).
After Joker's Wild was off the air, Tic-Tac-Dough replaced it and that stayed at 730 until Wheel came around (by this time, the Muppet Show was done and TTD was moved to 7pm with Wheel coming on at 730pm). When the Muppet Show ended, other game shows filled the 7pm slot (I could be wrong about the shows, but I remember in this era watching Bullseye and some other game shows in the pre-primetime slot). After the first year of J! at 4pm, it was moved to 7pm.
So WPVI always had this 7-8pm syndicated slot, with 730 always having a game show. J! was also moved to make way for Oprah, which mostly aired on ABC stations (I think only two markets did not have Oprah on an ABC station for most of her run).
I may have some of the specifics wrong, but just wanted to put out there the idea that history plays a role in what airs at what time in various markets.