Well, I am not in it for the precision. I like the casual feel of hand-arranged frames on a wall. If I attempted to measure and make it uniform (like I did on the record album wall), any irregularity would drive me nuts-o.
|Before: A Newly-White Wall|
I do use a level to make the frames straight -- I'm not that sloppy.
Then I fill in with the smaller frames. The key here is the use the same black frame/white matte combo. Then they look cohesive no matter how they are hung.