Love them or hate them, there's no denying that throw pillows make a sofa look inviting. But exactly where is the line between a cozy number of throw pillows and an inconvenient, excessive amount?

“Blankets and throws are not always meant to be flung” over a sofa’s arm, says Standefer. As an alternative, she likes to create a “sofa carpet,” an English decorating tradition in which a large ...