Your feed should be the main diet. Everything else is considered "treats". Not that anything you've listed is bad but if you think about it the purchased feed is blended with well balanced nutrients and amino acids, etc. It can be the sole food but that get's boring and chickens are a great way to not waste food scraps and leftovers. Not to mention veggie and fruit scraps make the eggs taste better.
Rule of thumb is 10% of diet is "treats". Obviously if you've a lasagna that nobody in the house liked you can feed to the chickens making more than 10% feed for day and have no worries. You can think of the 10% idea on weekly basis.
People like to up the protein content during hard molts (yearly hen molt) hoping/knowing it will shorten the period of non laying. And Black Oil Sunflower seed is an excellent treat in winter as it's extremely high in fats that are easily converted to energy for self heating, also are 14% protein.
My chickens get garden culls, pulled weeds and such plus leftovers from refridgerator in late spring to early fall for treat and fridge culls and sunflower in winter.
Mine never took to the cracked corn in scratch but was still an excellent way to train them to come when called. Stopped purchasing scratch all together.
ETA- To vary protein intake and when with a mixed age flock you can use gamebird/turkey feed. A gamebird starter is 28-30%, grower 21-24% and finisher 16-18% depending on manufacturer. It doesn't have the added calcium but laying hens regulate themselves for calcium if oyster shells are provided on side or handfuls tossed few times a week.
