My vet (well, my personal advisor, not my pet's vet as she's my partner's sister) doesn't recommend Jimbos or Max more than once a week because it's very fatty. Their coats can go shiny if they have a too high fat diet, so it doesn't necessarily mean that the cat is healthy. In saying that, if you've had no health issues, and they get other food too, it's not going to be worse than feeding say, all dry food or whatever. I think the key is make sure they get all of their nutritional needs, and not more.