Quote Originally Posted by wbJohn View Post
I know this from my kite flying days. We use Spectra/Dyneema lines (75 to 150 feet long) that need to be exactly the same length for dual and quad line kites.
This points out one instance where I DO think millimeter precision is important - anytime you need to make 2 spliced items of exact same length. Pairs of dog bones used in bridge hammock suspension, for example. It might not matter if each one is a half inch or so off from "nominal," but it definitely matters that they are identical.

And you're completely right about Amsteel or others stretching back out under loading. I always notice how stiff whoopies or CL's are when taking down my suspensions compared to what the cordage is like before any loading is applied.