The LIE girl I know would eat mostly chicken in hot sauce and rice which is easy to make in a rice cooker. I never knew this but it turns out that rice cookers are not only for cooking rice. You can steam veggies and even cook chicken in them, which may be why Asian people love them so much - for their versatility. She'd usually steam yams in it.

Otherwise she did meal prep like @Adam Strange describes, which I think a lot of people do if they are working full time and don't want to eat out every day, since eating out is not the healthiest option. She bought these plastic trays that were sectioned into three compartments. Then on Sundays she'd cook a large portion of chicken, toss up some salad, steam some veggies, buy dressing in small little packages, and fill up eight trays for Mon-Thu, since salad and veggies don't keep fresh the whole week, and on Friday it's easy to eat out or figure out something else for your meal. This way you're doing cooking only once or twice week.

There are also companies that offer meal prep services which both the LIE and the LII girls have used. They deliver you the entire meal so you don't have to cook yourself. Some services deliver the ingredients which you then prepare yourself and learn how to cook at the same time. I don't have much experience with these, but you can use them for the months when you're really busy. They probably use the cheapest ingredients so it's better to do meal prep yourself. This looks like a good summary - link.

Crock-pots / slow cookers. Not enough experience with this but I remember some students used them. The slowest step is cutting up the vegetables and the meat, then you put it in, pour in water, and let it simmer over night or over the day, and come back to several portions of ready-to-eat soup. I personally like fresh and raw foods so something that has been cooking for hours isn't very appealing.

Cooking with roommates. So this is what they do in co-ops and shared housing. This is when one person cooks for the entire house or for all the roomates and you switch duties every week of couple of days. Saves on time. The con is that you won't be always eating what you want, you need to figure out finances for sharing food, and some people aren't great cooks. This is what I did with an ESI roommate where she cooked breakfast on one day and I cooked it on another day. Our tastes were similar enough that we could easily share food.

A lot of people are doing intermittent fasting diet right now, which is what I've switched to as well even before I knew what it was called. I've found it easy to follow and it does save on food prep time. You can either lose weight on it or maintain the same weight, and even gain weight, so it's not really a diet. With intermittent fasting you basically don't eat much for the entirety of the day, then have one large meal and perhaps a snack closer to the evening. Many report feeling better and sharper if they are not having three meals a day and not snacking all day long, and you only have to fix up one meal. Also has health benefits - link.

Outside of that there are lots of simple recipes that don't take more than 15-20 minutes to prepare, and, not going the full extent of a week-long meal prep, it's easy enough to fix two portions enough for two meals. Easiest is probably fried eggs and veggies, where you fry some onion in a pan, add vegetables like tomatoes, zucchini, cauliflower, and/or mushrooms, and break 2-5 eggs over it. By now I've gathered a small collection of these, so combining easy simple recipes with intermittent eating diet the cooking doesn't take much time at all.

You can also do what SLIs do and optimize your environment for efficiency. Simple things like put your salt, pepper, and spices on a small rack right next to the stove, make sure things are easy to reach, clean any cooking utensils as you're cooking once you no longer need them, flush the plate and frying pan right away so that they don't dry out which makes it harder to clean, make sure you have sharp knives (I've underestimated the importance of this before), and so on. This way you don't have to spend a lot of time on clean-up and just moving around the kitchen.

There is also a rather ingenious way of providing prepared food for yourself, which both an SLI and an IEE I knew did, and this is by working at a restaurant or a grocery store where they allow for their employees to have either free or discounted meals. So there's that option.