If I understand your question, you're saying that because Safari can still access porn and Covenant Eyes won't catch it then it's pointless. I'd probably disagree only because the next step would be to set up the restrictions on your phone with your accountability partner and turn off Safari. Then your only browser would be Covenant Eyes or X3 which would track the sites you visited. I'd agree that both solutions aren't really complete but even if they both offered jailbroken apps that ran in the background, we'd then have battery problems.

Another option mentioned yesterday was to just have your accountability partner check to see if you've cleared your browser history when you meet.

After you install X3 on your phone, you turn on restrictions and shut Safari off. I don't believe X3 will work unless Safari is disabled. X3 does a good job showing how to do this on video.