This testing has solved numerous issues for us in the past, although since it was being run daily sometimes we needed to re-release problem packages after fixes were rolled in. We have gotten the run time down considerably now (less than 1 hour for all tests) so we have adopted the policy that we will be running this test suite now as a Pre-Release process for updates so that if there are problems, we can address them before release.
The t_functional suite lives on github and we would be happy for people to help us develop new tests or make the current tests better. You can download and run the tests on a VM or machine that you can afford to reinstall (the tests are destructive and the machine is left in a state that is different than when the tests start, so it should never be run on production/important machines). You can also submit new tests or updates via github. We use the CentOS-Devel mailing list for discussion of these tests and for requesting changes.
Please help the CentOS Project make CentOS Linux better by testing, designing and submitting to our t_functional suite.