Hanging pictures can be hard work, my husband used to say whenever we moved, which was often, that he didn't want me to hang any pictures until he could help. Well, that was all well and good, but his sense of of timing did not coincide with mine; invariable I hung them myself long before he thought of his plan to help. He was only worried about holes in the wall. He is a perfectionist and always wants the fewest holes possible.
So here is a little story that illustrates why pictures may never get hung in a home. On our last move, the focal point in our living room was over the sofa - which by the way should always go on the longest wall, not the shortest. Anyway, these two large pictures needed to be hung, not staggered as I suggested earlier, but right at the same level next to each other.
So my husband gets to it right away, knowing if he doesn't I will. He pulls out the leveler, the long tape measure, hammer and nails, and a pencil to mark the wall!!#$% no holes mind you, but lots of pencil marks. At any rate, he seems unable to measure it correctly, has several holes and a half hour later, the pictures are still on the floor.
I finally told him to move over and took two nails, hammered them into the wall where I thought they should go and hung the pictures. OK, they were not perfect, but only off a very slight bit. I took one down, moved the nail and voila - they were hung.
Needless to say, my husband put his hands up in the air, trying to hide his surprise and admiration that I accomplished the task efficiently and perfectly, put his tools back and never asked to help again. So hang those pictures at all costs, if you need to move them, you can always make another hole.