A limitation, which can be removed immediately after identification, is just an obstacle.
But a limitation, which cannot be removed for significant time duration, is a constraint.
All obstacles can be and should be removed immediately, but a constraint cannot be removed in the immediate future.
There will always be a limitation that cannot be easily removed – it could be either capacity of the resources or customer demand.
This means that the only way we can improve the system is by exploiting the constraint.
If there is a constraint, which cannot be expanded upon immediately, it is obvious that managers should be exploiting it fully.
Common sense does not mean that it is commonly held sense.
Bottlenecks are hard to spot because so few can see the whole picture.
People at different links might only see what is immediately upstream or downstream from them. So when there is something really visible like 100 ships waiting to unload, it’s easy to think that the problem is at the Los Angeles/Long Beach ports.
But that wasn’t really where the bottleneck was. Rather, it was at distribution centers closer to the consumer. Trying to increase ports’ capacity by running them 24 hours a day didn’t help, because the problem was there was no place for the containers to go. A lot of warehouses were and are still chockablock with inventory, so they have difficulty unloading containers. That backs up the whole chain—all the way to the ships sitting at sea.
It’s like a game of telephone. The message gets garbled pretty quickly. This is a common problem in operations. Managers throw money at what they think is the bottleneck only to find that it didn’t help much because the real bottleneck was somewhere else in the system.