About getting into a "food rut": I just did a Google search about what the different "food groups" were, and came across charts that had from 5 to 11 or more different "group" categories. Granted, some of these "groups" ranged from misleading to useless: one chart had all fruits and vegetables classified as providing "fiber" (which they generally do), but the "protein" categories only included either milk/eggs or meats/fish, while all grains were included in the "carbs" despite the fact that they are also significant sources of protein (and fiber, if they're whole-grain). Bacon was included in the "fat" group.
I'm not 100% sure... but I think these different "food group" schemes are meant to help people avoid patterns of eating that will leave them with some sort of dietary deficiency. Those of us who follow a vegan diet have eliminated at least two or more of those "groups", depending on what foods are considered a "group" in a given chart. I don't obsess over it, but every now and then, I take a minute to think about whether I'm getting into a rut.