Been stick welding for decades, and my preference is thinner rods to get "suitable" current, it's OK to run big rods, but unless you have a decent machine, you don't get a good "run" done lots of TIG welding, both Stainless and Aluminium, but not a lot of MIG, though I am pretty confident, all that said, I am not a welder (boilermaker) and never have been, just done some TAFE courses and home experience.