Iso
My leaders are a 12/10/8/6 taper. When you divide the 6 strands at the tippet end for the Shorb Loop or ring you end up with a leader that is 3X the single strand strength.
Most of my fishing is with 9' 4 or 5 wt. rods and I prefer a 7' leader made from Berkley 4# "Transition Gold" fluorocarbon as it seems to sink faster than even Berkley "Vanish". If they made the "Transiton Gold" in 2# I'd be using that.