If they are eating feathers they are craving protein in my opinion.
Layers won't usually overeat. I offer free choice feed 24/7 to my layers. Now if they are meat birds (cornish crosses) that is different and you should tell folks if they are.
It is important if you want eggs to give them high quality feed- eggs are protein. To make new feathers and to make eggs they need lots of protein.
Layer feed is usually 16% protein, and chick starter/Flock Raiser is 20% usually.
I'd give them a feeder full of laying pellets or unmedicated chick starter/Flock Raiser (with oyster shells on the side to help with strong eggs since the chick starter and Flock Raiser don't have enough calcium for layers). The 20% protein feed you could just give them for awhile until their feather picking is gone, then go back to layer pellets/crumble.
Some people do this every year for the molt, to assist feather regrowth.
If they still insist on feather picking you can put pinless peepers on them (chicken blinders).
A lighter weight hen will eat about 4 oz. of feed per day, to give you an idea of how much feed they should be going through. This will vary all over the map, depending on if free ranging and the temperature outside. In cold weather they eat more and if free ranging they usually eat less if forage is good.