I have trapped cats consistently for 20 years but I usually have 3 or 4 ridges, or spots and 2-5 traps at each location. In some I’ll hike 15 minutes or a half hour, others  are closer to a road. Basically I traps salient feature or spot and try to find weather proof sets there. I always have snow. Over the years I’ve picked 2 or 3 places at each general location , moving things over the years  as I saw tracks and trying to learn where cats want to be.   In December I have to be very careful with Christmas tree hunters, so often start in mid- December. Because we have snow I am confident I don’t miss many that visit an area, some years I’ll go a whole 2 months and never see a track in some places, other years I’ll get a couple.   Overall I average 2 cats year, but for me one a year is enough to make me go back out.   Our numbers, and consequently quotas, have dropped over these 20 years. I think this is much more indicative of cats in accessible areas than overall population but I don’t know.. 
   I learned originally by watching John Graham videos and I remember in MT he said a spot that catches a cat, even though it might take a few years for a repeat, is a good spot.   If I divided total trap nights by cats caught I bet I’m closer to 1:500 but it’s not really fair because if I was more stingy with traps I could lower that, but I miss one occasionally or see a track and can’t help putting out more traps. I am in central Montana, some rocky forested country with a little sagebrush. I’m not a particularly good or dedicated trapper but my biggest limitation is time and gas.   So 8 cats in 500 nights sounds like I’d died and gone to heaven! 
     I snowmobile my marten line, often 30+ miles once a week and I’m sure there are cats around but haven’t seen a track, even with lower snow years in several years. My guess is that density and trapping success is largely related to density.   I think those eastern MT/WY longliners are or were running 100+ traps in good open habitat.   And they could undoubtedly read country a lot better than I can.