Theory of Constraints

If

Every chain has one weakest link. Improvement anywhere else raises local efficiency while total throughput stays flat — and often makes things worse, because the faster upstream stage simply piles more work in front of the real bottleneck.

Then

“Find the constraint, exploit it fully before you buy capacity, and subordinate every other stage to it. Then measure again — you have just created a different bottleneck somewhere else.”

Unless

The Constraint Moves — relieve one and another takes its place, so a process permanently optimised around yesterday's bottleneck starves at the new one