Variety of Foods - Just Wondering

You may have heard once or twice that one should eat colorful and different kind of foods as much as possible? But if your'e like me, sometimes pretty lazy at cooking, especially if preparing the food requires several different ingredients and takes a lot of my time, when I really want to spend it doing something much more important. I do love eating and I do enjoy very much food that someone has poured their heart into (not literally...) and the meal was made from good, fresh ingredients and has lots and lots of different colors, flavors and lots and lots of vitamins in it.

How important is it to get fruit, vegetable, meat or beans every day? If it's totally okay to eat for instance bread and coffee for breakfast, meat, potatoes and salad for lunch or dinner, fruit, berries and yogurt at snack time and bread and tee for supper, would it also be okay to eat only one kind of ingredient for half a day, or maybe even for one whole day, and something completely different the next?

So what I'm thinking is that if one eats for instance only strawberries on Monday and switches to something like potatoes the next day, would ones diet still be versatile enough to keep one healthy? You know, just asking... for a friend.

Something like this:
1st day Strawberries
2nd day Chicken
3rd day Carrots
4th day Bean
5th day Pineapple
6th day Beef
7th day Orange
8th day Potatoes
9th day Beetroot
10th day Kangaroo
11th day Lettuce
...and so on.

Then again one could pick the item one eats every day by color:
Monday: Red or pink
Tuesday: Green
Wednesday: Yellow
Thursday: Brown
Friday: Purple and blue
Saturday: Black or white
Sunday: Orange

Or go alphabetical! One ingredient per day. Like this:
Apples, broccoli, corn, duck, eggs, fish, grapefruit, ham, insects, jellyfish, kale, lobster, mushrooms, nuts...

How about if one ingredient would be for one week? Change it every Sunday. Like Jesse does. "This week I have been mostly eating nuts!"