Multiple grounds

Cables
1

If we had a shield of its own concentrically around each signal conductor, each connecting to the source end, and had also a “main” shield concentrically around the lot of those, would this act to shield the signal wire from ground noise more, with two layers of essentially the same shield as cover? If the outer larger concentric shield has over twice the surface are of the signal-wire-concentric shields, would it act to lead noise to source ground “before” the inner shields are affected capacitively much at all, giving clean grounds surrounding the signal wires?

Separating the signal conductors with their own shield tubes decouples them capacitively, no?
What about leading all signal grounds to their separate grounding box(es)?

2

Been done for over 50 years or more. Multipair audio cables typically have each pair shielded and then a shield and jacket around all the shielded pairs. The early stuff from Belden didn’t have the individual pairs jacketed, just shielded. Today from about the 1980s forward we have shielded multipair cables with each pair jacketed as well. Must nicer to work with, especially on breakout situations.

Good engineering practice dictates the overall shield be connected to the rack or frame ground at both ends so it acts like a metal conduit. The individual pair shields are handled in various ways based on the application.