Early in beaver career I did try adding some weight to chains, but it ended up causing more entanglement and failures to go sown the slide than I could live with. In 1500 beaver give or take a hundred, I can only think of one that was free to go down the slide and chose not to. Tangles are another story. And I did put the lock on backwards once. Operator error in most cases of it not being at the bottom.
Had one really odd one a few years ago. Had a camera watching 2 snares about 10 feet apart, one at waters edge and one high and dry. Starting getting pictures in the night, saw a catch in the one at waters edge so I shut the camera off to not waste image transfers and battery life. The camera was set to send an image every morning at 7:00, so it did send that one but I did not pay much attention. That day I arrived at around 3:00pm, and removed the beaver from the snare at waters edge, then looked up and to my surprise there was a big 50 pounder in the dry snare. As I looked closer, I could see no disturbance, even my split stick support was still in place not knocked down. Every weed was still standing. That beaver had not even made a single circle. So that got me wondering if it had been caught moments before I arrived. I went back to the 7:00am picture and there on the edge was a big beavers head. From at least 7:00am to 3::00pm it had not made a single round, it was not tangled, alive and alert, just chilling out in that one spot all day at the end of a tight cable. Strange things happen sometimes