The final rivet of the top skins took a total of about 6 hours per wing. Four hours for bucking the main sking; One hour for the top row and one hour for squeezing the rear spar. We used the ole square bucking bar on the top row because we wanted to keep it off the tank and leading edge skin, and we wanted it to fit in between clecoes. It worked good. I have no gap between main skins and the LE or Tank skin, and the scarf joint is almost flush with the tank skin (almost).