I think that thin ca is the best choice (for me) for wing ribs and the like. The instant set of thin ca on the light balsa to balsa assemblies makes for a short process. I talked with a friend that has built many models over the years and was told that Two to Three 2oz. bottles is normal on an average size kit. What he stressed was ""use what it takes to make a good glue joint"
It is my understanding that much of the glue weight evaporates upon curing.
Besides more weight="bigger engine and go faster to keep it in the air"
Marco.