Should I attach the vertical supports for book shelves at 16" or 32" intervals? The previous house had 24" centered studs and I had installed an upright on each stud which seemed like a lot of metal. Since I've severely thinned the books, I don't need as much shelf space and have plenty of the vertical pieces to do the closer spacing if you think that is necessary. The shelves are veneered plywood so I'm hoping that they will be stiff enough for the wider spacing.