I have a number of Harry Higley's books. One of them has many useful suggestions when building a plane. One of them concerns building the wing: First one wing is partially built and the second wing is then built onto the first using the correct dihedral (if used) that way both root ribs come together perfectly and allow for better sheeting. The builder then finishes building both wings. I've tried it both ways and actually like Higley's idea.
It does require the builder to have a good size table or bench to build both wings at once.