Power polygon and matching ground

For power polygon that primarily carry DC, how critical is it that it is located above a ground plane?

If it is important, how crucial is it that the polygon completely overlaps the ground plane beneath it?

Additionally, if overlap is important, how significant is it that the ground plane remains continuous and is not split by traces?

A ground plane under a DC power polygon is important because it helps reduce noise and electromagnetic interference (EMI). It also helps ensure that power is delivered consistently and prevents power spikes.

Thank you, ahsrabrifat.