Lab
Bottlenecks and System Shape
When one narrow constraint governs flow through a system, every other part adapts around it—removing slack elsewhere doesn't speed things up, and the bottleneck's physics determine what the whole system can do.
Then check the pattern
A factory line has five stations. Four finish their work in 2 minutes; one takes 8 minutes. Speeding up the four fast stations to 1 minute each changes total throughput by how much?
Cuts total time in half—twice as fast overall Saves 4 minutes—now 12 minutes instead of 16 No change—the slow station still takes 8 minutes Increases risk of jams at the slow station
Answer: No change—the slow station still takes 8 minutes. The slow station is the bottleneck—output can't exceed what it produces. Speeding up the other four just makes them wait longer for the eighth-minute station to finish. Flow rate equals the slowest step's rate.
Why does a single chokepoint force other parts of a system to operate below their capacity?
Running upstream steps faster wastes resources when downstream can't keep up Organizations prefer uniform speeds across all stages Faster upstream work lowers quality through rushed decisions Systems naturally slow down to match the average speed
Answer: Running upstream steps faster wastes resources when downstream can't keep up. If you produce 100 units upstream but the chokepoint only handles 50, the extra 50 pile up or get discarded—effort spent making them is wasted. The rational move is slowing upstream to match the bottleneck's rate.
A rail network has one bridge shared by freight and passenger trains. Adding tracks everywhere else in the network does what to total daily trains?
Doubles capacity—trains move faster on uncongested track Nothing—the shared bridge still limits daily crossings Increases passenger trains by shifting freight to trucks Reduces delays by spreading demand across more routes
Answer: Nothing—the shared bridge still limits daily crossings. The bridge is the system's constraint. More tracks elsewhere let trains reach the bridge faster, but can't push more trains across it per day. Total throughput stays capped at the bridge's crossing rate.
An office building has one elevator serving ten floors. Installing faster computers on every floor changes elevator wait times by how much?
Shortens waits—people finish work faster and leave earlier Lengthens waits—more people try to use the elevator at once Zero effect—elevator capacity is unchanged Depends on whether people walk stairs instead
Answer: Zero effect—elevator capacity is unchanged. Faster computers don't change how many people the elevator can move per trip or how fast it travels. The constraint is the elevator's physical capacity and speed—unrelated to what happens on the floors.
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