I’m trying to understand the best practice for filling unused areas on signal layers. I’ve seen conflicting guidance: some recommend leaving copper thieving to the fabricator for copper balance, while others use GND pours to improve shielding and provide additional return paths. Poorly stitched GND pours, however, can potentially affect return currents and controlled impedance.
For those designing with high-speed signals, what is your practical rule of thumb? Is there a point where one approach is safer, or a minimum via-stitching strategy to avoid return path issues?