My birds have a varied free range environment here; under spruces, horse pasture, weedy areas, intermittently mowed areas, and under fruit trees. They wander, at most, over about six acres around their coop,; maybe 500 ft. from the coop at most, and never far from tree or shrub cover. After each generation sees a hawk attack, those 'wide open spaces' are much less attractive to them!
I don't have game breeds, who would likely be braver, lay fewer eggs per year, and so have lower nutritional needs overall.
Now that we have six or eight inches of snow on the ground, nobody wants to go out anyway! They will go to the horse's round bale, and gradually to the barn, in a few days, but that first snowfall discourages them a lot!
During warmer weather, they do eat less Flock Raiser, getting something from foraging, but never will they ignore those feeders!
Mary