I don't keep collars on mine either; and Phred would often mind me that they NEED ID on them. What if the house caught fire while I was out? What if a tree limb crashed through a window (I could see 7 of my 10 marching up the branch and out, while the other 3 are in hiding from the invader.)

So if you keep it on, tighten it so that can't happen again.