Hey guys back here with one last dilemma for my new apartment (co-op)

I have this very nice thin black wall shelf thats perfect for holding a few knick knacks and what not. I had thought a perfect spot was above the TV but the only problem (at least I think) is that the shelf is NOT longer length wise than the tv. Most of the pics i see all over the internet show a shelf going past the length of the tv. (see example photo)

Is this a rule of thumb of sorts for the 'above the TV' spot? I'll admit it does seem nicer when the shelf is longer.