As presented at the Gearset DevOps Summit on November 2. This version has no animations in it, so some diagrams may be odd/confusing but the number of slides is modest. A version with animation is available here: https://speakerdeck.com/aidanharding/philosophy-challenges-and-opportunities-of-devops-on-salesforce-with-animation.
In this presentation, we looked at the questions behind DevOps on Salesforce: Why is it hard? What is the real source of truth? What approaches can we take to make progress?
I encourage you to keep things simple and use just enough process/tooling to get what you need.