I use a 3/32" land, 3/32" gap, or pretty close to that. On an 8" pipe with an 1/8" rod for the cap I use one bead, no weave, don't even know if I've tried a weave with a xx10 rod. Mine is more of a swirl as I go down. On a 12" 5g sch. 40 I just run a bead for the cap. I don't think you'll need double stringers until you get into the heavier wall pipe or on a branch. Others with WAY more experience will chime in soon...good luck with it,
Shawn
Great question, and the choice sometimes between a single cover (slightly washing) vs two stringers sometimes will revolve around how much heat you will be putting into one single spot slightly oscillating vs two side by side covers with cooler, narrower stringer beads.
I have an extensive Naval shipyard background (tig and stick with pipe), along with commercial shipyards too, and when you have any sort of misfit on the pipe with any irregular gaps the extra time you spend weaving and washing the bead adds alot more heat to the area (think of a square inch) and then puddle control starts to waver. I'd always choose to run an extra bead fully under control than risk a wider wash that is just on the edge of loss. Just my opinion.