Yes, all the time. Being pessimistic helps, but you also need good - and more importantly, self-aware - engineers, and a senior management structure that's willing to work with you.

The keys, basically, are realistic estimates and a willingness to de-scope. If you're willing to launch something with a few bugs and some small features missing, and to improve them in subsequent releases, you can hit any reasonably realistic launch target.

In the days of shrink-wrapped software, those bugs and missing features might have been unacceptable, but in a world of web apps and of app stores with automatic updates, iterative follow up releases for polish and improvements and even to incorporate user feedback should be a routine part of any software process.