It seems like most lunch skirts for sale are thick/bushy. I'd guess 40-60 strand. But when I see a pro post a picture on Facebook of their punch rig, the skirt is always thin: 20-30s strand.

I've seen this from Russ lane, Brandon P, and some others.

Are thinner pinch skirts better? When is it better to throw a thinner or thicker skirt?

Thinner allows it to slide through veggies easier and it will fall faster.

Thicker can be tougher to get through cover...but slows down the fall and offers bigger profile.

I agree. If you are fishing thicker vegetation go with a thin skirt. Thinner vegetation, I go with a thicker skirt.