What Goose is doing, welding on galvanized or painted metal, is extremely difficult, no doubt about it. Welding on clean shiny new metal is a lot easier. Can you get watertight welds with a lot of starts and stops? Maybe. The problem is cold starts. Sewing it up like your doing, then grinding it off, and making another pass works good, just takes a lot of time. What your doing is getting rid of the edges, which like to melt away. Just keep practicing. Crank the voltage on that little machine wide open and tune the wire. Watch the puddle. You have to move fast enough to keep from burning through, but not so fast that you leave the puddle behind. On some practice metal, try slowing down till it burns through. Watch what it looks like. The idea is to move just a little faster than that, kind of right on the edge of total disaster.