In my experience, a team can run on just-in-time planning, the one simple task list, and the experience of their senior people for quite some time. It's even Agile: People, not processes. But what we lose is the ability to grow more senior people for when we run out of the ones we have just now.

The Very Smart organisational systems have inefficiencies, but they also have affordances. And more importantly, they have the structure to let multiple people poke at them at the same time, and allow people to learn and make mistakes without (normally) breaking everything that's currently in-progress.

Trying to run for too long on the one "real" list is a recipe for burnout and tech debt. And ensuring the team is using the right model at any given point in time is an art I'm not entirely sure I've mastered.