As a side note, if you ignore some of the distant "rimshot" stations (ie, channel 3 in Ely, NV really can't be received off-air in the SLC metro), one thing that becomes clear is how few markets of any size had more than three or four commercial VHF allocations.
In major markets, NYC and LA each had seven commercial VHF allocations (although one of the seven has been used by a non-comm station in NYC for the last fifty years or so). After that, the only other top 50 market to have more than four commercial VHF allocations is Seattle/Tacoma. In smaller markets, Honolulu also has five (although the fifth commercial allocation wasn't added until the eighties), as do Boise/Nampa/Caldwell, ID and Anchorage, AK.
And even the number of major market with four commercial VHF allocations was pretty low: Chicago, Philadelphia/Wilmington (but the fourth commercial VHF slot is filled by non-commercial WHYY), San Francisco/Oakland, Washington (DC), Saint Louis, Miami, Phoenix, Portland (OR), and Denver. An additional two (Charleston, Salt Lake City) were added in 1980. And a four commercial VHF allocation market that used to be a small market (Las Vegas) has grown up into a major market in recent years.
So, really, if you go back to the the fifties and sixties, the overwhelming majority of major (top 50 market) commercial VHF allocations were in areas with three or fewer commercial VHF stations, which guaranteed a network affiliations and the profitability associated with running a major network affiliate. In turn, that meant that these allocations weren't going to be allowed to remain fallow for long.
The only economically marginal major market VHF commercial stations that I can think of from those days were WNTA channel 13 in NYC, channel 12 in Wilmington,DE (I can't remember the commercial call letters for this station), and KTVW channel 13 in Tacoma, WA.