Track the unplanned work and the impediments as their own signal, and the system starts telling you where it breaks. The early instinct that later became control charts on two streams.
A long, close reading of Poppendieck's talk on how plans quietly become the thing we serve instead of the thing we're building. Cost of delay, queues, and the economics underneath the manifesto.
The marshmallow challenge is the whole argument for shipping early and often, in eighteen minutes of spaghetti and tape. Prototype, test, and stop mistaking the plan for the product.
My earliest operating-model thinking, before I had the vocabulary: headcount, process, and tools as constraint-led capacity work, and the support team as a feedback loop, not a conduit.
Rigid priority-number columns mislead, and I said so in 2008. What I'd do differently now: weight by cost of delay and treat ordering as a live conversation, not a sorted list.