Most people have food out all the time. Chickens don't usually eat all at once... They graze. So when they are hungry they will get food. If It were me I would like to eat whenever I was hungry... Then you know that they are getting enough. Chickens getting fat is a rare thing if they have room to walk around. There metabolism is very good. Hope this helps
A production hen will eat between 1/4 to 1/3 pounds of feed a day. So with your 8 they should be eating at least 1 pound a day. When you ration feed, of course they will act hungry when you feed them they want to make sure they get their share before its gone.
Slipped a gear there. Two pounds for eight birds is about the amount they will eat of feed. If you allow for other foods the amount of bought feed will be less. I think that amount is figured to be the right amount of nutrition and calories for them to be healthy and productive.