Honestly, this is just a numbers thing. If you have "enough" animals you will most likely see the same pattern. I would have said the same thing years ago. My first breeder male was, and remains a pig. I think he may have missed one weekly meal in the entire time I have had him. He really, really wants to be a big boy. 95% of his offspring are also gluttons. As to what to do with the rat, I almost always have something else that will eat it. I have a couple animals, including the male mentioned before that have no problems going back and forth between live and FT. I avoid live for those animals that have never had it. None of my holdbacks have ever had live. Before I had so many animals, I would just "off" the rat and freeze it. I can understand that this can be difficult for some to do, but if you have enough animals for enough time it will eventually be a problem that you will have to face.