I'm not at all surprised that the preponderance of responses here basically invert the question: when DO you use a recipe? Those of us who do the family-and-friends cooking in a house almost every day know most of our dishes inside out, and can ring changes on them pretty effortlessly, even invent new ones based on two or more. After a long time I just revisited one of my faves from the '70s, the Chile Relleno Casserole, and adapted a larger recipe to an 8x8" pan. As soon as I'd made it I understood how it differed from the ones I remembered (more custardy than eggy, not cheesy enough) and have since rewritten the recipe. After I do that one I'll probably remember it from then on.