When you're just starting out in a system, every incident is a novel, never-before-seen issue. That's putting aside existing sources of knowledge like coworkers and runbooks of course, but I've had to do "software archeology" on lots of stuff because coworkers are gone and docs are wrong. But that's where you build up that intuition, like how the company typically builds things, how deployments usually work, what's that terrible load bearing service installed 10 years ago and not updated since, etc. Yeah every T3 incident eventually is novel, but being able to cut out the non-novel parts helps a lot