This was a strong specific long run: 17.3 km at 6:08/km, with fresh legs, very good sleep, and excellent sensations throughout.
The half-marathon-effort block was not perfectly clean because of traffic, semaphores, and route interruptions, but the workout still delivered the intended stimulus: a controlled faster segment inside a shorter long run.
The best signal is that the effort stayed manageable and heart rate came back down when the pace eased. This supports the current sub-4:30 marathon direction without needing to turn every Sunday into a test.
Takeaway. Keep using structured faster blocks, but separate rehearsal from racing. The August 9 half-marathon workout should not simply replace the real 21K race on August 23; it should be adapted as a controlled rehearsal.
Next step. W10D2 Intervals. Short 10K-pace repetitions. Keep them sharp and repeatable, using lap average rather than instant GPS pace.