straight on to be pretty deep, around 30" or so. I've installed cleats to the wall to support the back of the shelves, but I need a front edge stiffener beam to prevent any sagging. Would I be able to get away with just one in the middle of the seven foot long shelf straight ahead, or should I put one in each corner and to support the side shelves which I'm not as concerned about. Or is two not enough either? Should I have one for each side? Two for the middle? Feel free to let me know just how dumb I am in your responses.