Most operational problems present as a symptom: a delayed launch, a quality issue, a frustrated customer. The instinct is to fix the symptom. The discipline is to trace the work backward until you find the single bottleneck that all the symptoms point to. Fix the bottleneck, the symptoms resolve. Fix the symptoms, they keep coming back.
How to find it
Walk the process backward from the symptom. At each step, ask: what is this step waiting for? Where does the work sit longest? Where is the queue longest? The bottleneck is the step everything else feeds into and almost always the step that takes longest to clear.
Why teams miss it
Bottlenecks are usually held by people who are already working flat out, which makes them look like high performers, not constraints. The team protects them by routing work around them, which hides the bottleneck instead of fixing it. A protected bottleneck is still a bottleneck, and it caps the throughput of the entire system.
What to actually do
Reduce demand on the bottleneck, add capacity to it, or redesign the process so it is no longer in the critical path. Anything else is rearranging the symptoms.