A client's React class-to-hooks migration had been "90% complete" for fourteen months. The last 10% contained every hard problem the team had been avoiding. Gradual migrations don't fail at the start — they fail when nobody decides to finish.
A critical notification service was processing 50,000 messages a day. When it started silently dropping SMS, it took a week for anyone to notice — because the alerts were going to a Slack channel that belonged to a team that no longer existed.
A client's 45-minute data import gradually became a 14-hour ordeal that bled into business hours, tanked dashboard performance, and made the analytics team distrust their own numbers. The fix wasn't what anyone expected.
A client's real-time notification service kept crashing every few days. Restarts fixed it temporarily. The root cause was 14,000 zombie WebSocket connections from clients that had disconnected days ago.