This Video gives tips for TIG welding a 1G flat butt joint and how to watch the puddle sink to make sure you are getting penetration,
A tee joint fillet weld test in 11 ga thickness usually requires penetration into the root but not all the way thru the back side
Sometimes when you are out of practice, its good to just practice until things feel natural again. I welded a 3g butt on 11ga aluminum and the first try did not go so well, so I settled in and just stacked a few beads on scrap until things felt more natural and comfortable
A Macro Etch test also known as a cut and etch test is a very valuable teaching tool. Its a destructive test but it can verify settings and technique and since you see the results in a matter of minutes, the puddle is still fresh in your mind. Did it penetrate like you thought? One Cut and Etch ...