The final shakeout did exactly what it needed to do: 4.4 km at 6:49/km, normal legs, good sleep, controlled heart rate, and no discomfort.
The pace felt slightly heavy only because the run was deliberately slow. There is no meaningful warning signal in the session and nothing left to change in the preparation.
Sixteen weeks of marathon training are complete. The long runs, the official half marathon, the marathon-pace rehearsals and the taper have all been absorbed. The next run is the race.
Takeaway. Keep race day simple. Start controlled, settle around the planned marathon rhythm, use lap-average pace rather than chasing instant GPS, and trust the fitness built throughout the block.
Next step. W16D7 Marathon. Race day. Run the Buenos Aires Marathon with a controlled sub-4.