If your dog still has the stitches, then keep the collar on whenever the dog is alone. A lot of people say to keep it on all the time so that they get used to it, but I personally believe in giving the poor thing a break, so when someone is with them and can keep an eye on them, then take the collar off. If the dog no longer has the stitches, but is still chewing the area then it might be worth asking your vet to check and see if it has become infected, and if it is they will give you something to clear it up.