I've done both. For me one of the major factors in deciding to kill or leave and let die is the cohesiveness of the group they live with.
If they are a family/tribe then these days I leave them to die with their tribe, usually givng pain relief for the last few days.
It's more complicated with injuries I think. One can look at an injured chicken and thiink there is no way they will fully recover and in trying to keep them alive one would just be prolonging the pain until the inevitable conclusion. They can hang on to life with some truely horrendous injuries. It's having the experience I suppose of knowing what will heal and what probably won't. Internal injuries are particularly difficult to assess.
If they are a family/tribe then these days I leave them to die with their tribe, usually givng pain relief for the last few days.
It's more complicated with injuries I think. One can look at an injured chicken and thiink there is no way they will fully recover and in trying to keep them alive one would just be prolonging the pain until the inevitable conclusion. They can hang on to life with some truely horrendous injuries. It's having the experience I suppose of knowing what will heal and what probably won't. Internal injuries are particularly difficult to assess.