GreenMonti, I agree that equipment makes less of a difference than the welder. A good welder (and I'm not claiming to be a pro by any stretch of the imagination) can make good welds with fancy or very basic machines.
My logic on starting with thick material is this: I teach complete noobs how to get started welding at a local makerspace. Typically people who have never touched a welder, or have basic knowledge with a MIG at best. It takes them a good while to get used to the motions of TIG. They get caught in this loop where they can focus on 2 things at a time but ignore the 3rd. So they'll watch their arc length and their filler, but forget about the foot pedal. Then all of a sudden they have a puddle growing out of control so they shift attention and ignore arc length, so now they're wandering up to a 1/2" arc. Repeat.
When I teach I stick people on 0.09" coupons and bits of 0.083" square tubing. It's not monster thick, but it is thick enough to resist the insta-burn through that really thin stuff will do. I tell them to stick to that stuff until the muscle memory starts to build up and they can run a number of beads in a row with minimal issues. Once they can do that, move on to material that's similar to what they want to work with for their project. I don't tell them to stick to the thicker stuff until they're a pro, just until they acclimate to the motions of TIG. In just about every case this helps them learn faster than if they try to jump right into some more specialty material.
