I find it best to weld a dot at a time. Weld dots a few inches apart, then when cool weld dots between those dots. Keep it up until the seam is filled.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.