The Metropolitan Museum of Art regularly posts short audio/visual tours from their collection and this one on Frank Lloyd Wright's living room of the Little House features a few views of a pair of wonderfully long, long window seats bookended by perfectly proportioned bolsters.
These pictures make a strong case for making one long cushion for a window or bench seat instead of breaking the space up with 2 or 3 (or more!) cushions.
It's graphically bold and comes with the added benefit of allowing the user to lie anywhere they want without encountering a break from one cushion to the next.
An interesting choice was made to have the cushions come up short in width to allow the bolster to rest inside the space between the cushion and the wall.