If you go the continuous delivery route, I think you will need a way to canary a pending release. I also think you need really good production monitoring solution that can trigger a rollback to the previous release automatically (assuming you have a way to mark a release as "appropriate to automatically rollback").

The amount of tests you need to automatically release "bulletproof" code is staggering. In one successful example, I noticed there were about 10k tests that took about 30 minutes to run (before the code could be checked in). I would think you need to use TDD to feel confident that your tests are good enough.

The other aspect of CI/CD that bugs me is the dramatic increase in complexity. I thought KISS and Occam's Razor would kill the CI/CD efforts. Moving to weekly release seems a lot simpler and I doubt most teams need to release changes much faster than that. With CI/CD, if you have several components and lots of shared code then managing which component to update given dozens of changes affecting different components is a nightmare. Unfortunately, once you start using CI/CD, there is no going back (often for political reasons).