It seems to me that drags and their use vary as much or more than staking. First off, I can comment only on coyotes, cats and to a much lesser extent fox. There are other larger animals that I have experience with but I'm not allowed to address these, based on the distribution of shearable hair relative to their perianal areas :twisted: .
Just about the only time I've ever buried a drag under a trap is when I make a dirt hole. I make relatively few dirt hole sets but those that I do make are big holes. In my country digging holes that deep (to bury /pack a drag and bed a trap) is frequently a real effort too impossibe.
I most often scratch a ditch, for the chain, from the trap of to the side and usually the back of the trap bed. This allows for a shallow hole for hiding the drag. I lay the grapple in its' bed and hammer the down side point into the ground. The chain is then layered along the axis of the shank, covered and packed down. I blend the drag bed as I do for the trap bed. I try to keep the drag close to a clump, bush, log boulder or what ever I have for a backing and usually put some sort of blocking guides about to keep critters from stepping on or approaching the set over the drag bed.
The second most common way I deploy drags is to purposely tangle them among limbs of trees or bushes. I do this when staking is impossible and /or I have directions I DON'T want the critter to go. RdFx mentioned that they often head down hill...along my line most of these so called "hills" require repelling gear and a drag in the tree is in order. Also, along traveled roads, a drag often can be stretched to its' length in the desired direction of travel tangled or hammered in. Once caught, the critter can move easily only in the general direction of the grapple's anchoring location. If the grapple is in a "remote" bush or tree there will you find your catch. I know fox men that use these approaches to allow greys to get concealment and protection from other predators including those equipped with large talons. In any case you can influence the direction of escape away from, for example, a roadway or toward a concealed hide.
I think that one needs to consider the adage, "best laid plans" when choosing locations for drags. Look 360 degrees and ask yourself where the catch will likely end up if they head in any one direction. Concern yourself with roads...they can be real hard to follow especially if the rancher drives by before you. Hard frozen ground can be very problematic especially if cover is distant and, snow after a catch in open areas is just slow going, if possible at all. While on the topic of snow, consider how you will know if you have made a catch...often he ain't gonna be sittin at the bed! I use a metal detector... no beep is a good thing!
Something to consider, especially if you have widely varying cover types, is to have some "extension chains" along. In potentially problematic areas or weather conditions you can add 5 or 10 feet of extra chain...not many coyotes will travel far, even in loose sand on 15 too 20 feet of chain and if they do you'll be able to track em. Also, you can use this rig to anchor your catch to even more remote locations.
I use 100% Wimberly plows. The addition of this 3 or so inch inverted "V" connecting the bends of the grapple points makes a remarkable difference in both "hang time" and drag marks...which mean fast / short trackings.
Hope this helps some!
