There should be a requirement that people responsible for QA of submarines construction be aboard while taking the sub to test depth for the first time.
You know, way back when I took a rock climbing class the rule was who-ever tied the knots was the first person on the rope. It made for very conscientious knot tying. Same thing here. If you say it's good, put your life on the line with the others.
Probably the only saving grace here is that this was just a test. As long as the manufacturer was on the ball and doing things right, the steel is probably just fine. But the test was supposed to help ensure no mistakes were made. Adds risk to every one of those ships out there. Maybe the steel is fine, maybe it isn't and they are eating into their margins of safety on every dive.
The shipyard often has representatives aboard until the Navy buys off on the vessel.