One of the issues of using the older posts from the pre-release era is the settings have changed since then.
This demonstrates a fairly good workflow for testing fabric.
I think variability in fabric, as you mentioned with the thread count and weight, is quite the issue. For fabric, and for almost any material, I end up doing a test. Even if it is Proofgrade. One never knows how a particular design will come out on any materials.
One issue is always holding the fabric. Heavier weight fabric isn’t too bad, but lighter stuff can blow and flop around. Use the sticky cutting mat method. The other thing is putting finished items in for cutting or engraving. Like a pair of jeans. How do you fold and get it set correctly without the crumb tray.
Good luck.