However, all the "layers" and locks and alarms and whatever become moot if you forget to engage them.
Two weeks ago, packing our travel trailer for our second trip of the summer, I went ahead and put a couple of our handguns in the camper (locked in the GunVault and cable-secured) overnight because we were leaving town before dawn the next morning. When I awoke early and went out to the camper on my driveway, I found ... to my great chagrin ... the camper door wide open and the GunVault laid out on the floor where someone had obviously entered, found it, and tried to open it and/or take it with them. Obviously, I had forgotten to lock the entry door to the camper. Fortunately, the GunVault and cable were sufficient "layers" for this incident and prevented a robbery, but a dead-bolted door should have been in place to prevent the intruder from even getting to that point.
This was a vivid wake-up call for me ... forgetting to lock the door was a very stupid and risky error of negligence which I shall not repeat.