# Theory of Constraints Every system has exactly one bottleneck that limits its output. Fix that one and everything improves. Fix anything else and nothing changes. Resist the urge to optimise everywhere at once. It feels productive but wastes effort on non-constraints. --- ## The five focusing steps Goldratt's method is almost embarrassingly simple: **Identify** - Find the bottleneck. Where does work pile up? What's everyone waiting on? **Exploit** - Maximise what you can get from the constraint without major investment. Don't let it sit idle. Prioritise its workload. Remove anything that wastes its time. **Subordinate** - Align everything else to support the constraint. Other processes should run at the pace the constraint can handle, not faster. Overproducing elsewhere just creates inventory and confusion. **Elevate** - If exploiting isn't enough, invest to increase the constraint's capacity. Buy more, hire more, redesign. **Repeat** - Once you've fixed this constraint, a new one will emerge. The work is never done. --- ## Where the constraint hides The constraint isn't always where you'd expect. [[Execution trap]] builds its entire argument on this. When results disappoint, the instinct is to blame execution. But the constraint is rarely headcount - it's the system. WIP piles up, variety slows processing, decisions wait weeks for sign-off. The essay shows a team of forty with forty-seven items in flight: Little's Law predicts the eight-month lead times before you look at a single person's performance. The constraint is the environment that effort operates in, not the effort itself. --- ## Why local optimisation fails British Cycling's "improve everything by 1%" works when factors contribute independently. Most business processes are serial, though: work flows through sequential stages, and throughput is gated by the slowest one. Improving a non-constraint creates the illusion of progress while the bottleneck stays unchanged. Goldratt put it sharply: *"An hour lost at a bottleneck is an hour lost forever. An hour saved at a non-bottleneck is a mirage."* Cost accounting makes this worse. It rewards high utilisation everywhere - spreading fixed costs across more units lowers "cost per unit." So managers keep non-constraints running flat out, inventory piles up, cash gets trapped, and the actual bottleneck sits unchanged. The numbers improve while the business gets worse. Throughput thinking asks different questions: what is the impact on the rate at which the system generates cash through sales? That cuts through allocation games to focus on what actually limits performance.