What if it's both high-priority and hard? Like you find out that a fundamental part of how your product works causes data to be miscalculated in a certain scenario, and rewriting it while maintaining backward compatibility is a multi-week task? During which you will get more high-priority bugs...
This article sounds like a fantastic sentiment, but even a small project of a few hundred thousand lines will completely fall over as soon as it's released into the wild. And if you had a medium-sized project you wouldn't even make it past the point where internal testing is doing large scenario evaluation.
That said, if it works for your team, go for it. Never throw in more process than you need, but don't assume that what works for small teams scales. Unless you're trying to sell a book or consulting services, of course :-)