This long run was a strong aerobic signal: 15.4 km at 6:25/km, with normal legs, controlled effort, and no late collapse despite starting in cold conditions.
The run confirms that earlier easy and long-run guidance was too conservative for good days. A fluid aerobic pace can now settle closer to the mid 6:30s, and sometimes faster, when conversation and mechanics remain relaxed.
This does not mean every long run should become marathon-pace work. It means the marathon target can now be built around a more ambitious working goal, with sub-4:30 as the main direction and sub-4:35 as a solid fallback.
Takeaway. Easy does not mean artificially slow. Use effort first: long runs can settle around 6:25-6:45/km on good days, while recovery pace stays slower only when the body genuinely needs recovery.
Next step. W06D2 Intervals. Three sustained threshold repetitions. Keep every block strong, even, and repeatable using lap average rather than instant GPS pace.