I definitely believe in a DevOps process, though a thoughtful, incremental one. I think this is the best way to develop software, whether you release every day or every year. Yes, you can implement DevOps and release once a year. You just end up tracking, testing, communicating, and being ready for that once a year release. Of course, I bet you don't release once a year since I'm sure you'll patch the system at least once.

One of the core principles of DevOps is to use automation where you can. Remove humans and ensure that repeatability is possible for moving software from one machine to the other. Communicate, test, and then alter your process to work better. This requires the monitoring and input of humans to examine the process, but they shouldn't be involved in deployments other than approving them. It's too easy for an individual to make a mistake.

However, DevOps isn't a panacea for building better software. Witness the issues at Knight Capital, where they went from having $364mm in assets to losing $460mm in 45 minutes. Mostly because of a problem deployment, where an engineer didn't deploy code to all the servers in their farm. Certainly a clean deployment to every system might have prevented this, but the reuse of old flags in code is problematic, as is leaving old code around that could be executed.

In addition to moving to a DevOps mindset, I'd also say that you should be sure that you follow good software development practices as well. Clean out old code (including database code) and be very, very careful about reusing any part of your software, including flags, for a new purpose. It's far, far too easy to make mistakes here.