From Alabama Chanin:
The Poncho is a versatile cover-up and a great layering piece. It's just a strategically sewn rectangle of fabric. An Alabama Chanin favorite, it looks beautiful in every color and fabric style. Ponchos cut across the grain stretch out of shape over time, particularly around neckline (since fabric cut on the cross-grain stretches more and has less "memory" than fabric cut with the grain). In our studio, to counter this tendency, we always cut two ponchos at once by folding the fabric in half along the grainline to create a double layer and then cutting through both layers, making one for ourselves, and one to gift to a friend.