Horses are stoic by nature and don’t always exhibit outward signs of stress because that would make them more vulnerable to prey appearing as a weak individual in the herd. Providing multiple locations to eat from encourages movement and allows them to choose where they are most mentally comfortable. An enclosed confining area (stall or shed with sides) would be most human’s choice for physical and mental comfort in the elements, we are not prey!
My very vocal mare taught me this concept and it all made sense. She had a stall that included a 2 acre turnout. When it rained I provided multiple hanging bags in her stall, no hay outside. Even though she had free choice hay she would nicker to me when I refilled the bags that were getting low. It finally occurred to me she might want to eat outside. I provided Standard Hay Pillows in the turnout and she immediately walked outside and started eating in the rain; her mental comfort took priority over any physical comfort she experienced in the stall. She will choose the stall only if the elements are extreme. Interesting feedback from customers duplicates my experience; if they provide a Standard Hay Pillow in a stall with an adjacent turnout the horses will pick them up and carry them outside in the rain and snow!
Providing your herd a choice of where to eat gives them the opportunity to be as mentally comfortable as possible and encourages a more natural lifestyle.