Most of the best trappers and longliners gang set each location with 3-5 traps. Personally when I stop the truck at least 3 sets are going in the ground. Like my good trapping buddy always says, “can’t catch a triple on coyotes with 2 traps out... but to answer the question, 30-35 traps in the ground gang set at the 8-12 best travel corridors and pinch points.
For me, and I'm not an expert by any means but if I'm going to spend time and gas money I'm going to put out everything I got it simply ups my odds. Use some with different combinations of lures and baits some with just urine some with just lure and no bait just make every set different.
I've mostly learned to set on sign; tracks, droppings, snatches of hair at fence crossing, etc.. I'll still set at really coyoteish looking spots but usually the coyotes are not smart enough to utilize these ideal locations and I end up pulling an empty trap. I'd also set more than 1 trap, 2 to 4, at each location. The number of locations just depends on the amount of sign.