When I heavily got into spey I bought all my big eyed dumbell flies from the shop and followed the recommended standard of the T-14 & T-10. It made the learning curve horrible with the rod that I first bought, super fast scandi rod. After many days out with frustration. Lines have come a long way since I started... and Skagit lines were a great training wheel. Once dialing in the sustained anchor casting I found that I wanted to push the limits of distance, which came the frustration again.... the frustration of tangled loops. After buying a handful of rods and toying with countless lines I settle with a 32' head that can cast some 5/32 dumbbell eyed bugs that I tie myself, tho these days for my prefered spey tactics is a non 12.5' of T-7 and I swap my flies according to the water I fish. I make a pattern, I duplicate it and revise it. Then I make a dumbbell version, then a smaller version. That way if I feel im not getting down or dragging i can swap just my fly to my conditions. Also most importantly my average length leader is 3'-4'

Another tactic that took me a while to catch on to is when im fishing light is to cast upstream as the line straightens take a few steps down stream allow your presentation to sink, once you feel that you're in the zone hold on tight!