Fixed tracks and vias only kept other nets away, so a pin fanned out to
its plane was routed to the plane again, beside its own fan-out. Pins,
zones and planes that fixed copper of their net touches now form one
connected group: a fanned-out supply pin needs nothing more, a fanned-out
signal routes from its via, and copper touching no pin or zone adds
nothing to route.
Tracks and vias already on the board were ignored, so other nets could
be routed straight through them (the flight controller's 82 GND
stitching vias and its guard tracks). They are now copper of their net:
other nets keep a pad's distance from them in the grid, the exact check
and the room engine, and they add no connections to route.