Should the 3D skybox have the same shape as the playable area?

[[Soap] SteelCroix]

When making an 3D skybox should the space in the middle be the same shape as the playable area? Or does it even matter at all?

 

[Crowbar]

Not unless you're making a perfect connection between real world and 3d sky, which is usually avoided and the boundary is camouflaged, hidden, so it doesn't draw attention.