When you run agents in parallel to move faster, the thing that breaks is not the producing, it is the quality. You end up with a pile of output and no trust in any of it.
What worked for me was separating the two jobs completely. Agents produce, freely and in parallel. Then a hard gate decides what survives: a reviewer that scores each output against a written rubric, and a second pass that actively tries to break it and find where it is wrong.
The key is that the gate is real. It has a clear standard, it can fail things, and a reviewer error counts as a fail, not a silent pass. Once the gate is trustworthy, you stop treating scale and quality as a tradeoff, because volume flows through the same standard every time.
Producers make things. Gates decide. Keep them separate and you can scale without lowering the bar.