Everything depends on the exact situation
RI Stomasis Burns Retained Eye scales Dehydration etc are easily treated at home
Vehicular or animal injuries/bites can have hidden complications such as broken ribs entering stomach cavity and causing peretonitis so vet check if I consider they have any chance; otherwise euthanise
Head injuries often mean lower jaw damage so if that is suspected I encourage the snake/lizard to bite
[prefer a snake bite any day to a big lizzie]
If it cant bite properly I euthanise them
If it can quick vet check then treat at home
So every situation is different with differing procedures