There are several charts in text books and on web sites that depict the penetration profile caused by different grind angles of tungsten electrodes.
I like to see things for myself so I tested 3 very different angles on pieces of 2% lanthanated electrodes ...all 3/32" (2.4mm).
I let the piece cool completely in between beads and kept the arc gap the same for all three beads.
Travel speed as constant too on a welding turntable.
I cut the beads all the same distance from the start point and polished and etched using a stainless steel heat tint removal solution.
The problem with tig welding carbon steel square tubing is that is is easy to melt thru and pull oxides into the puddle. When that happens, the puddle gets weird. Pulse settings can help.
One of the biggest struggles for new aluminum TIG welders is learning to feed TIG wire. In my opinion, it's one of the hardest parts of aluminum TIG to get ahold on.
Whether its a vertical weld or laying flat on the bench, the same techniques apply, but getting comfortable can be the main thing. The ABC's of welding are ...Always Be comfortable