If it's a consumable, they should have tested at least one hull to destruction, just so they could be sure of it's failure modes.

Based on what I've seen, it doesn't sound like OceanGate had decided on a fixed number of dives. Instead they were planning to continually monitor it (x-ray scans after every dive and real-time acoustic monitoring during the dive) with the assumption that they would get some warning before it failed.

That makes sense, but to me that just means "keep dropping it until it implodes and then you can find out exactly how many dives it's good for". I still see absolutely no reason why humans should have been inside that thing. It's easy to criticize from an armchair, but goodness it just boggles my mind.

That puts a new spin on a “brittle unit test”