I'm having two different experiences.
I have 4 free range hens who mostly eat in the woods and around the yard, though they have layer mash free choice, and they are locked up at night. I have not kept records but feel they eat about the way imp's do; I buy 25# bags because it takes them several weeks to go through one.
I also have 50 - 12 week olds -- well, it was 50 til we put 10 in the freezer yesterday. They went through 100 lbs. last week. They are also locked up at night but have a 75'x75' yard available all day. They are doing some damage to the weeds in it but there is a lot of green left. But it is about 5-6 years' worth of weeds grown up in what was farmland before, so there is not much grass, and no trees. Their crops were almost entirely full of feed when we butchered. They spend a few hours AM and PM pecking and eating weeds but tend to spend the hot part of the day in the coop. Maybe if it were true pasture, or woods, they would eat less feed. I have maybe 400 sq ft of it sectioned off and planted; when I open that up, it might help, too.