"Bushing bind?" Leaf spring bolts/shackles: how tight?

When swapping leaf springs out, I gather that it's standard practice to snug up all of the bolts (but not torque them down), put weight on the suspension with the car on the ground, bounce it a few times, then tighten up the bolts on the mounts and the shackles.

This is basically the procedure that I followed when swapping out my stock leaf springs for the heavy duty Hotchkiss lowering springs/1.5 shocks and I assumed everything was good. Yeah, the rear suspension was really stiff but I assumed that's how these new springs were supposed to be.

Last week, I noticed that my car was sitting a tiny bit higher on the driver's side and I decided to try to try again...after loosening up all of the bolts a bit, I noticed that the suspension, while still pretty stiff, was suddenly quite a bit more compliant and I could move the car quite a bit more when pushing down on the bumper...and it got me wondering if maybe this is how the were supposed to be and perhaps I had been in bushing bind all along.

So...what's your procedure? Should the bolts and shackles be torqued tightly?