Bottlenecks: Finding the Leverage Points
A bottleneck limits what a system can accomplish. Find the constraint, check whether your metrics reflect the outcome you want, and test whether proposed changes improve the flow of work. Incentives and gradual changes in practice can undermine an apparent improvement.
THE IDEA
A busy team can improve many individual tasks without improving the result that matters. If finished work is waiting for approval, producing more work upstream may only lengthen the queue. Start by finding what limits the system, then check whether your measures and incentives help you address it.
1. False Proxies
A proxy stands in for an outcome that is hard to measure directly. It becomes misleading when people can improve the metric without improving the outcome. Hours worked can reward being present rather than useful work; pressure on customers can raise satisfaction scores without improving their experience.
Campbell’s Law describes the pressure to corrupt a social indicator when decisions depend on it. Goodhart's Law is commonly expressed as: when a measure becomes a target, it ceases to be a good measure. Ask how someone could raise the number while making the underlying result worse.
2. Theory of Constraints (TOC)
Eliyahu M. Goldratt’s approach focuses improvement on the constraint that limits throughput. Its focusing steps are:
- Identify the constraint.
- Exploit it: use the available capacity more effectively.
- Subordinate other work to it: coordinate the system around the constraint.
- Elevate it: add capacity or make a larger change if needed.
- Repeat when the constraint moves.
TOC evaluates changes through throughput, investment and operating expense. Making a nonconstrained activity faster may do little for overall throughput.
3. Diminishing Returns
Increasing one input while holding others constant can eventually produce smaller additional gains. Excess fertilizer can harm crops; extra study time can displace sleep. Adding people to a project also adds coordination costs, so it is worth checking what the extra capacity will actually accomplish.
4. Pareto Principle (80/20 Rule)
The heuristic that roughly 80% of consequences come from 20% of causes directs attention to uneven contributions. The actual shares must be measured; the rule does not establish a power-law distribution. Possible examples include 80% of profits coming from 20% of customers, or 80% of crashes from 20% of bugs. Use the idea to look for concentration, rather than forcing observations to fit it.
5. Via Negativa
Before adding a process, ask whether removing an obstacle would help. Cutting unnecessary approval steps or deleting confusing prose can be useful. Removal also has risks: a control may look unproductive until it prevents a failure. Check what the proposed subtraction does and what depends on it.
6. Regulatory Capture
A regulator can come to serve the interests of the industry it is meant to oversee. Dependence on industry information, lobbying and career incentives can contribute. Examine who influences the rules and whose interests are excluded; a particular regulatory arrangement alone does not establish capture.
7. Boiling Frog Syndrome
The boiling-frog metaphor describes failure to respond to gradual deterioration. Track changes against an explicit baseline so that a succession of small departures does not disappear into a new sense of normal. The metaphor is useful for discussing scope creep, declining quality or a deteriorating relationship.
8. Normalization of Deviance
Diane Vaughan’s account of the Challenger disaster examines how repeated departures from a standard can become accepted when they do not immediately produce catastrophe. A launch that survives does not by itself establish that the accepted risk was sound. The same question applies when teams repeatedly bypass a safety check or a trader takes larger risks after earlier bets pay off.
9. Cobra Effect
An incentive can make the problem it addresses worse. The name comes from a story about a colonial cobra bounty that encouraged breeding snakes; ending the bounty then encouraged their release. The general question is how people might respond to the reward in ways the designer has overlooked. Rewarding closed support tickets, for example, can encourage staff to close unresolved cases.
Applying the Models
- Find the constraint that limits the result you want.
- Check whether the metrics reveal that result or reward a substitute.
- Look for an obstacle you can remove, and check what its removal might damage.
- Concentrate effort where the evidence suggests it will matter most.
- Review repeated exceptions and gradual departures from standards.
- Test how people could game a new incentive. Where regulation matters, examine who shapes the rules.
After a change, measure its effect on the system. A successful improvement can move the constraint elsewhere.
When to use it
Diagnosing and fixing a process backlog in manufacturing or software by systematically applying the Five Focusing Steps of TOC.
Evaluating a performance bonus structure by red-teaming it for the Cobra Effect before launch.
Removing a recurring source of delay before adding another scheduling tool or approval process.
Auditing a startup's growth metrics to distinguish true, healthy growth from false proxies like vanity metrics, and checking for normalization of deviance in sales or engineering practices.
FROM THEORY TO EVERYDAY LIFE
In practice
Fixing a Software Development Slowdown
Suppose a software team finds that its deployment pipeline limits delivery. It stops treating commit counts as a measure of useful output. Investigation shows that 20% of flaky tests cause 80% of pipeline failures, so the team repairs or replaces them while preserving coverage. It also examines why people bypass the pipeline for hotfixes. It then measures whether delivery improves and checks where work now accumulates.
Corporate Strategy and Perverse Incentives
Suppose a CEO rewards higher Net Promoter Scores. Sales staff pressure customers for 10s, while product quality deteriorates. The score stays stable and conceals the problem. The team needs other evidence, such as complaints, retention and customer interviews, before choosing which features or processes to change.
A MOMENT TO REFLECT
Put it to work.
What currently limits the result your team can deliver? What observation or small test would show whether increasing that capacity improves the whole process?
Can you identify a metric you track that might be a false proxy? If you stopped measuring it, what behavior would change and what would be the second-order effects?
Think of a slow decline in quality, health, or a relationship you witnessed. What were the early signals of the 'boiling frog' that were ignored because they were normalized?
Often confused with
References
- The Goal — Eliyahu M. Goldratt (1984)
- The Challenger Launch Decision: Risky Technology, Culture, and Deviance at NASA — Diane Vaughan (1996)
- Antifragile: Things That Gain from Disorder — Nassim Nicholas Taleb (2012)
- The Unanticipated Consequences of Purposive Social Action — Robert K. Merton (1936)
CONTINUE THE CONVERSATION
Source texts
- The Great Mental Models Volume 3 Systems and Mathematics