The above picture shows a Nest from a Cut Plank Corner Board. There is still a hump at the middle. It only reduces the angle. As most Nests buyer still consider this as a Corner Nest. This type of Corner Board was favored many years ago when the Crescent type was not available then.
There was no option to choose from. The left-over planks were cut to make into Straight Corner board. The left-over Planks were used and this saved the builder some money.