Well now that’s a little bit of a trick question. Sometimes we do 2 sets, sometimes we do 3. The general rule of thumb USED to be 75%.
You bring up a good point though. If an arteest creates a design actual size for the Men’s print, and it has a 45 lpi halftone in it, and we reduce it down by 75%, that line count jumps to somewhere around 60 lpi. In my opinion, one should design their Men’s size art at about 35 lpi. Then the reduced art would have a line count around 45. This is only half the battle though, Many times the art is so fine, I’m zooming in studying individual pixels. These are T-SHIRTS, not INTEGRATED CIRCUITS! A good t-shirt design should be able to be seen in it’s entirety in about .40 seconds. From about 10 feet.