I trap every year, and the height that gets me bees is about 10 feet up. I spent 4 fruitless years here trying to catch at least one swarm, and I had decided to hang them from a french cleat I had rachet strapped to a straight trunk, as high as I thought comfortable. That turned out to be about 5 1/2 feet. I finally realized all I was getting in the traps were red wasps, brown widow spiders, and ants.
Since those critters like being closer to the ground, hanging them out of their comfort zone, and putting baits of grape jelly, and peanut butter mixed with borax in the hives, I got 5 swarms out of 6 traps last spring. Using the same 6 traps, I caught 2 in 2014, 1 in 2015, 1 in 2016, 0 in 2017 and 2018. Since I usually get around 66%, I was getting frustrated.
That is the one thing I did before 2014, tie a harness on the traps, attach a line, a rock to the free end, toss it over a branch, and pull it up. The entrance can't spin around. You want to secure the trap with the free rope, and tie it around the trunk of the tree to finish.