One of the older guys I play with has limited mobility, so he has a short, choppy backswing and rotates 90° on his follow through, leaving him with his body and both feet facing forward, straddling where his ball had been teed up, with his club pointing straight downrange. He knows it's an odd swing, but it's his swing and he has no intention of changing it. He's in his mid/late 70s and shoots mid/high 80s, so he's happy enough with that.