Parent: stages-and-gates
- Funnel → tunnel — gates with no teeth; nothing gets killed → a rubber-stamp pipeline where weak projects sail through to launch. Cooper's #1 warning. A gate's job is to kill.
- Over- vs under-gating — too many gates = bureaucracy / slow (classic Stage-Gate's main critique); too few, or no verifiable "done" = chaos and big-bang delivery.
- Gaming the gate (Goodhart) — optimize the criterion, not the goal ("SOLID theater," junk tests written to hit coverage). The moment a criterion becomes a target it stops being a good criterion.
- A gate where there's no verifiable "done" — it degenerates into a human bottleneck or false confidence. Fix: fold that boundary into one stage, or mark it explicitly a human gate.
- Wrong stage granularity — too coarse (no checkpoint → big bang); too fine (you scripted the execution → it depreciates with the model = back to script / driver).