I am going to put 1x6 knotty cypress on the walls and ceiling of living/dining rooms. I am wanting to know if when I install it on the ceiling if 2 ft. apart nailing is enough. since that is what the trusses are centered on, the wood is tounge and groove also.If not what are my options? Also on the walls does it need to butt on studs? Could I cut the ends for splines to save waste if it does?