Wood glue works best when it is applied evenly to both surfaces to be joined. The surfaces should be flat and smooth. The close the surfaces can be clamped together to create the thinnest space for the glue, the better. Attaching wood on the long grain is much stronger than attaching on end grain. Think of the grain of wood as a package of spaghetti. Past does not spontaneously attache at the ends but it is easy to make a tangles mess of long strands of starchy pasta in a pot. Wood fibers are similar. The cut ends of the fibers are hard to join as a butt joint for the long strands of wood fibers can be pressed together with glue as a binder for a very strong joint.