When the second round was done, Chris did it again. At this point, the welds should all be about a quarter of an inch apart and ready for the gaps to be filled with a few quick tack welds. Don't run a short bead here-this is not stitch welding. Instead, tack-weld the tack welds together. While a trunk floor is not as sensitive to heat warping as a quarter-panel, the goal is still to keep body filler to an absolute minimum so the seam becomes invisible.