I'm not convinced that Oracle is doing a good (enough) job of testing their patches, or more accurately, they are not _able_ to do to a good job no matter how hard they try. Their support matrixes are huge, with many Oracle packages interacting with other Oracle software, along with the OS, and other vendors software. We caught a bug with a patch set, the first customors to find it. An older yet supported software version didn't want to play nice with a newer oracle application. I ment horrible service and a lot of downtime for our users. Unfortunately the problem only showed up under huge loads that we weren't able to reproduce in our test environments. Maybe Oracle should have more publicly available benchmarking software.. but maybe the marketing dept. nixed such ideas.
I wish Oracle would trim down their support list, and dump older versions of software from support. Oracle would be able to better test for strange and arcane interactions. Who knows, maybe they'd spend more time fixing security issues across their whole code base rather than in the one app a security advisory was published on.