Load testing would have to be quite advanced to find this, doing more than just simulating users for the most common features. It took more than 24 hours of real-world usage to visit sufficiently many niche code paths to fill the code cache.
I'm not saying it doesn't take effort, I'm just saying it can and is regularly done
Regression testing with speed. If you test your features as they're added, niche-ness doesn't matter - you know about it and test it
A regression test quickly turns into a load test if you do them all at once
To be clear, I'm not trying to twist the knife. I understand why it wouldn't be done. I just won't pretend it can't
I've been trying to avoid this 'hindsight is 20/20' thing...
I'm not trying to lay blame - just offer thoughts towards improvement, and encouragement against some defeatist thinking patterns
A lot can be done with very little equipment/time investment