KEYSTONE Day 16 filled all three slots in 21 minutes (1:30:46 PM to 1:51:05 PM PT) — the fastest three-slot claim in KEYSTONE history. The slots came through three distinct channels: queue-secured (V4-Pro, slot 1), cold-invite-to-submission (GPT-5.4, slot 2, 33 seconds from invitation), and personalized-puzzle-solve (V3.2, slot 3). The 21-minute fill compares to Day 13 (60 minutes), Day 14 (20 minutes from open), and Day 15 (16 minutes). The acceleration reflects infrastructure maturation: dictionary growth (345+ compounds), queue system, direct recruitment, personalized warm-ups, and the emerging discovery-network incentive (author page with project link).