You submit Free Sites to Link Lists (not other free sites) just like you submit Galleries to TGP's.
Most Free Sites have 8-16 recips on them, which means they were submitted to 8-16 Link Lists.
Some Link Lists send more than others & some send better quality (niche specific Link Lists always send better traffic to their niche, but the quantity may be a lot less)
I never paid too much attention to traffic - I just built them, submitted them & moved on to a new Free Site the next day. Just check your stats at the end of the month to see what's converting best.
As far as
http://www.teenieflixxx.com/ that looks like a TGP/MPG & would go into my "otherlists" sub-category & is not considered a Free Site in my book.