They are very important if the software is mission-critical or if there is some sort of physical cost to shipping patches. But if you can continuously update the live site its not that big of a deal if a bug gets out. It will be noticed soon, often by your users, and then you fix it and that is it.
This works if the developers and other stakeholders at the company are testing the product themselves and are responsive and can triage bug reports quickly.
Having an up-to-date schedule can often be unrealistic as there can be shifting priorities and developers should be flexible to move around and respond as necessary.