When the boards are tightly butted together, the adhesive should foam out of the surface of the joint, which protects the joint against moisture ingress. The adhesive should be left to dry, which further enhances the protection against moisture ingress.
Evidence of the glue should be visible on the underside of the boards, although does not need to be excessive.
For further guidance on the application of EGGER Joint & Joist Adhesive, please refer to our glue guidelines document here.