Whole oat flakes are not cut before they are rolled, so they remain the bulkiest of the rolled oats. Oats are frequently used as a cooking ingredient, as in haggis and some varieties of sausage ...
For grains, that ends up erasing much of the apparent time-saving benefits. I'll still use my pressure cooker to cook whole, bran-on grains, because it doesn't do any harm at all, but I'll do it ...
Just pour boiling water over the grains, let them stand for 15 to 20 minutes, then toss them with a fork before adding other ingredients or serving. To 1 cup of this grain Add this much water or broth ...