Usually I meal prep for 4 days at a time because it's easier for me and it helps me keep track of my intake. usually i'll have a portion of any greens, some fish as protein or other sources non red meats, and carbs quinoa, rice
Actually that's how professionals do it. When you create a menu, you list items that have common ingredients, or that you can create a new dish from the leftovers of another. Not only is it smart, it's economical. It also cuts down on the leftover themselves.
So yeah, prep. And use common ingredients for multiple items to cut down on what you are paying.
Whenever I cook, I'd make enough to last me a few days. I'd make something that'd still taste good (or taste even better) after a few days, like stews or spaghetti worth meat sauce. I especially love making slow cooker meals (usually stews) cos I just put all the ingredients in and turn it on before I leave for work, and it'd be done by the time I get home :)
I never know what I'm going to feel like eating in advance so I just cook everyday. I'm not one of those people who hates myself and thus can't eat only the same thing every meal. But I try to eat mostly veggies with a quarter of the plate for protein and a quarter for carbs (I don't feel full without them, plus they're good for yout brain).