> I'll extend my argument to suggest that most HNers are familiar with changes that can not be tested in isolation, simply because they require significant chan

> I'll extend my argument to suggest that most HNers are familiar with changes that can not be tested in isolation, simply because they require significant changes to the whole platform. [0] Flag days are still tested in a staging environment that represents production as closely as possible, and the overwhelming view of the kind of change you're talking about on a technical level is generally don't do that if you can ever help it.