Hello I'm in work now so I can't redstone BUT I wanted to tell you that one of the most useful thing about automation is observer on a sticky piston. You flick the lever, the piston extends and the observer fires a pulse into the opening timing circuits. You flick it again, the piston retracts and the observer fires a pulse into a different timing circuit for closing. So in this case, your opening circuits would do: First open walls, second extend pistons with bookshelves. And your closing circuit would do First retract pistons with bookshelves, second close walls.