I've been replacing the runs of RG59 throughout the house fed by the rooftop antenna with RG6 the cable installer guy gave me (he gave me around 150 feet, thank you). There was this last 12 feet of RG59 I hadn't done (was thinking how much loss would 12 feet of RG59 cost me). But I went and did it anyway, and it did make a difference. Looks like that fraction of a dB I got made it enough signal strength for the ATSC receiver box to allow reception and decoding of some marginal signals. Or maybe that old cable was bad...
Now all the TV coax cable (cable TV service, master antenna system) is all RG6. I used the old RG59 to fish the new RG6 runs thru the walls and ceilings.