Three moments, not one review
The standard arrangement is a single review before launch. It is the worst available position, because by then the purpose is fixed, the data is chosen, the architecture is built and the date is announced. A reviewer can raise concerns and cannot cause changes, which produces recommendations and a launch.
Three gates work better because each catches what only it can.
At inception, before building: should this exist, for what purpose, affecting whom? This is where the largest decision is available, and it is the gate most organisations do not have.
At design, before implementation is fixed: what data, what objective, what oversight arrangement, what happens when it is wrong? Changes here are cheap.
Before launch: does it meet the thresholds set at design, and what has the evaluation actually shown? This is the release gate from the AI QA cursus with the responsible-AI checks included rather than running alongside.
The economics drive the design. A concern raised at inception costs a conversation. The same concern at launch costs a delay, a rebuild, or an override, and the override is what usually happens.
So an organisation that can only build one gate should build the design gate, not the launch one. It is the last point at which the answer can still change what gets built.

