RELAX. I am not referring to offshore development centers, overtime on weekends, or working the night shift.
Have you been guilty of committing a change without running all the tests? One of the main reasons programmers don't run test suites before committing code is because of the length of time they may take.
Have you had enough opportunity to test the stability of your product? Longer-running tests are vital for identifying memory leaks and other stability issues.
Are you getting quality time on your performance testing environment? I have seen teams bickering with each other to get time on the performance testing environment.
Are there too many permutations to test manually? In many cases, your product is targeted to run on a variety of platforms.
Automated tests run during the night or over weekends will ensure that all these permutations are tested more often.