Gents,
I'm not an expert, but I have been told by one or two who would be regarded, even in this crowd, as being such, that the proper way to join panel or patches into panels is by recessingthe panel and overlapping the join. This improves joint strength and reduces grinding that causes heat and reduces panel stregth.
Care must be taken to ensure that water running down the inside of the panel, and it does run down them all, should not run into the recess for obvious reasons. A swage tool recesses about 10mm (1/2 ") so both the patch and the weld can sit below or level with the other panel.
See attached diagram. (I'm not a graphic designer either!)
'A' is the method some of you are professing as ideal.
'B' is the method that I have been taught. The weld could then even be replaced with a solder (I think) further reducing heat. If one were able, both sides of the join could be welded. The inside (the right side of the line) can be sealed with a suitable joint sealer.
Note: before anyone says "You shouldn't leave such a big gap" I have intentionally drawn the swage too big, otherwise it would look like a straight line with a little bump in the middle - That reminds me of someone.