Shackle angle in relation to spring pack

Let's hope I open a can of worms.

What's the optimal angle to have wiht your shackle in relation to your spring packs.

I see several YJ'ers up here that run 3.5 inch lifts and then add the 1.25 inch shackle. The shackle runs perpendicular to the ground, I can't help but think this wont' allow for that much unloading of the spring?

What's your guys take on this?

run it just about perpendicular to the main leaf, slightly on the acute side of 90°

Some guys like the angle quite a bit less than 90° to provide additional droop, but that will also stiffen the ride rate.