Hi Susan,
Rotation may or may not help depending on how it is done. If the person is stuck in a grain free anti large company mindset they may simply rotate from one small boutique grain free brand to another or change varieties within a brand and still have the same deficiency.
When rotating I think it is best done between types and companies to get the best benefit
Personally I don’t rotate foods anymore. I used to but found that her coat and skin suffered so her base diet stays the same to which I add a variety of fresh foods and canned.
