We have bitten off a big chunk in one bite in experimenting, maybe too much at one time, going in many different directions while challenging tradition and conventional wisdom, pushing the envelope with small traps, and also in the use of double door traps which by nature are "smaller" than the same size single door trap in trigger placement. Pushing to the max for space saving in the truck and for that we have found some limits in what traps can do with consistency and can not do, a learning curve with a short size, double door trap and different trigger, a lot all in one shot. Our experiments and feedback has been as much about size and length of traps and about double doors, as it has been about configuration in triggering, just seeing what happens while using small, short double door traps. No one had ever used an 18 inch single door trap for chucks or skunks until recently, let alone a double door trap that short, many changes at once.
Though animals can be caught in the shorties frequently, we promote longer traps for critters like coon, 30-36 in double door traps most of the time since the trigger is at center, and even suggest 24 inch traps for chucks if someone has concerns about really large chucks, though I have not seen issues with 18's for chucks in our experience. Some like 36 inch single door traps with triggers deep into the trap and I will be the last one to disagree with success or talk anyone out of what works for them. A longer trap of any kind surely has a lot less chance in back out as the trap fires. I once put some blocking in a chuck trap, 18 inch double door, since the landowner said it was "a small chuck." It wasn't a small chuck after all. I used green stuff used for blocking and I think the chuck might have pulled it in toward him and popped the trap. Had some chuck fur that one time, but that was one out of many dozens, maybe 100 or more. Never had problems with skunks.
In areas where coon run small, a 24 double door will work a lot of the time as I hear from one trapper in Ohio often, but we point out, it's probably a close call, and yet there are pics and stories of coon in 18's, go figure. Though we had never suggested he use 24 inch double door traps for coon I guess he misunderstood, but that's just we he did and has had success, which surprised us, but his coon do not run large. The issue becomes trap size and door configuration, not a problem in the trigger or double door itself, as Pesky points out, just using a trap a bit short for a coon that time for what was perhaps a large coon. If traps with 36 inch catch boxes are used, I doubt there would ever be much of an issue, just that the trap takes up more room, but room has to be secondary to results, of course. In all of what is written, and what we hear, there are still escapes often enough in the standard coon traps that have been around for decades, so perfection does not exist in any of those as yet, roll overs, or something gets bent, leaving only some fur behind.
In a single door 30 inch long trap the trigger is about 2/3 back into the trap in any trap, 20 inches or so, as opposed to only 15 inches in the double door. Trigger travel can be extended for deeper penetration before the trap fires on some traps if need be, but that too is a trade in the fact that a smaller animal might just pass through and slip by the wire without firing the trap if the trigger swings too far before firing. When you have a smart animal or a large one, its best to err on the side of caution and go a bit longer. However, listening to Paul, he says he has better luck getting the animals into the smaller traps over longer. As always, lots to consider, nothing written in stone or the same always, just trade offs. Equipment is important, but there is a skill factor and also just being on your game. I know when I haven't gotten a good nights sleep I am more apt to have issues, just not sharp.