During 12.04 development we will strive to ensure that Ubuntu Desktop works each day so that everyone can reasonably make progress with their development goals, rather than being blocked by poor quality in different areas of the product.

The flow as I envision it would go:
1. The ISO is testing in the morning for Europe
2. If the ISO is found to be acceptable, the QA reports such
3. If the ISO is found to be hard to use or test, the QA team reports as such
4. Ubuntu Engineering then investigates which package caused the breakage
5. The package that caused the ISO Is reverted
6. The ISO is rebuilt and step 1 starts again