One of the best things you can do in your organization is create a culture that treats obstacle discovery as forward progress. There is nothing more disheartening for an engineer than banging her head against the wall trying to debug some race condition only to get flak from management about why it isn't fixed and why it's holding up some milestone. The root of this problem is management that doesn't understand the problem domain, and is suspicious about whether the engineers are really working diligently. The proper response to obstacle discovery is to treat it as forward progress. Firing off an email to a superior saying: "I discovered an unknown race condition, let's see what we need to do to fix it," should be treated no differently than "I finished this feature." The presumption should be that the engineer used due diligence and the situation was unforeseen. Now, that doesn't preclude separate improvements to diligence procedures to provide better foresight in the, future but under no circumstances should anyone be blamed for discovering obstacles or defects and raising them. When your culture does that, all you'll get is shitty product.