Generally speaking, an odd number of frames on the wall is more aesthetically pleasing to look at. It also has the added benefit of being much easier to hang. You can center the first piece on the wall and then hang the next one either to the left or right. It doesn’t matter.
It makes hanging pictures over furniture very easy, as you center the middle piece with your furniture and then determine the space you need to leave between your frames depending on the size (length) of the furniture sitting below.
At Under The Roof Decorating we make picture hanging and wall decorating easy.