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Kindle Notes & Highlights
The more a person or resource is utilized, the bigger the lines (queues) get.
Queueing theory is a field of applied statistics that studies waiting lines. It allows us to quantify relationships between wait times and capacity utilization, even when arrivals and service times are highly variable.
In 1948, 3M gave its workforce 15% slack time, which years later resulted in sticky notes.5
Good metrics help us make good decisions.
The reduction of batch size is a critical principle of Lean manufacturing. Small batches allow manufacturers to slash work in process and accelerate feedback, which, in turn, improves cycle times, quality, and efficiency. Small batches have an even greater advantage in software development because code is hard to see and spoils quickly if not integrated into production.
Small batch sizes enable fast and predictable lead times in most value streams, which is why there is a relentless focus on creating a smooth and even flow of work.
too much WIP, unplanned work, neglected work, conflicting priorities, and unknown dependencies.
The Time Thief O’Gram shows who committed the crime and reveals how much was stolen.
Because WIP is a leading indicator, tracking WIP levels can signal problems early and warn you that things are going to take longer than expected.
cumulative flow diagram (CFD)—a stacked line chart that shows the amount of WIP and items delivered over time.
Good metrics for operations reviews include throughput, flow time, and time theft along with issues and blocked items.
Each contingency buffer opens the door to including more work. “Oh, that’s not due until Thursday. Can we add this other little fix in?”
Unplanned work can inflate tasks and cause variation. (Remember the impact of landslides on train schedules?)
The only time anyone does anything right the first time is when they follow directions given by someone else who has done it many times before.
Satisfy people with gradual change instead of dramatic change.
if WIP limits are ignored, think through what will happen to your flow time and chaos levels.
Scrum uses a time-box (usually two weeks) to limit demand, while kanban uses the WIP limit to constrain demand.
The reason I know a lot about making work visible is because in many ways (maybe in most ways), it’s easier for me to communicate visually than vocally.
