Increased twisting is a function of pin block tightness.
More twisting = more untwisting which affects NSL tension when the hammer force is removed.
The best way to measure NSL tension is as a function of pitch change after a test blow or the Bend Test. Often people want to complicate experimental procedures but we have to remember why we are interested in this subject - to produce superior stability.
Pitch change after testSharp = too high NSL tension.Flat = too low NSL tension.
There is a range of NSL tension that produce no pitch change when the hammer force is removed. This is called the Tension Band.
The Tension Band rises and narrows on hard blows requiring the NSL to be left high in the Tension Band for the best stability.
This model has been proven accurate by all the experimental data I've done.