I wanted to try and help clarify this burn through discussion. If you think about burn through, at what point of the weld bead does burn through take place? At the puddle, right? So, Sundowner is right. If you are using a pull technique in an already molten puddle and already extremely heated material, as you move along you are creating more heat and thus more molten temps than the thin wall can handle.......unless, of course, you stop welding and let it cool. With a pushing technique, you would essentially be pushing the filler metal into still solid material, which has not reached the temp of weld bead or puddle yet. does that help?
Also, on the issue about weaving your weld bead, especially when welding tubing. The claim is that when weaving while welding this tubing is it generates even more heat than necessary and can cause undercutting at the shoulders of your weld bead. Make sense? I never weave when I'm welding thin wall tubing, just a nice, even straight bead and has always worked well for me.