One fashion trend is to simply drape a sweater over the shoulders without making a knot with the sleeves. This is best with a heavier sweater so that it stays in place when someone moves around or with wind.
Having a sweater handy is a useful idea when someone is heading out on a cold day or when they are going somewhere cold. Having a sweater within reach around the shoulders makes it easy to grab. This can also add a bit of style to an outfit. A sweater over the shoulders turns a basic T-shirt and jeans into something a bit more sophisticated, making it a quick way to dress up an outfit in a pinch.