Welding . flux core or Mig ?

[Triple Jim]

Walking the cup is just a technique I mentioned after you brought up difficulty in keeping the tungsten out of the puddle.  I don't normally use it.  For long, straight welds on tricky material, specifically when I'm welding 2-stroke expansion chamber seams (20 ga. mild steel or 22 ga. stainless), I use a guide I made that clamps to the side of my welding table and supports my torch hand, letting me slide it along the guide.  It's a fusion weld, so I can steady the torch with my other hand too.  It takes the shakiness away so I can make a pretty weld.

As you said, you can rig up whatever it takes for the job.  There isn't one technique for everything.

[Rough Edge racing]

 I often MIG weld with two hands on smaller stuff for better accuracy...  My latest LSR bike frame is ready for finish welding so I'll try the TIG on it...

[Motu]

I use CO2 for my MIG at home, much cheaper than an argo mix.  I got an alloy dive tank for nothing, had it retested and filled. I can't afford a shield gas tank, but you can use dive bottles, even fire extinguisher tanks for CO2.  I've been repairing a rusty JD mower deck at home, the CO2 has been working just fine.