I didn't say there aren't any emergencies, but the emergencies are not on the same level. And I said they're highly trained, you don't need to convince me of that. Nor do you need to convince me they're important. Those are entirely separate issues.

Also what fraction of engine test cell use is for engine maintenance? Is it a big amount?

But if that kind of test goes wrong the main outcomes are "hit stop" and "oh no it's too late". An emergency like that is not where much of their expertise is needed, their expertise is in other parts of their job.