Every blank we print on gets washed ten times before we decide anything. Softness on the shelf is easy to fake with a chemical finish that rinses out after three cycles, so we ignore how a blank feels in the bag and judge it after the tenth wash instead.
What survives that test tends to be midweight ring-spun cotton somewhere between 180 and 220gsm. Lighter than that and the print shows through. Heavier and it stops being a summer shirt.
The other thing we measure is shrinkage. A blank that loses more than three percent in length is a blank that turns your large into a medium, and no amount of soft finish makes up for that.