Constraint Theory
Every system is limited by its weakest link.
Explanation
Business consultant Eli Goldratt's Theory of Constraints states that every system is limited by a single bottleneck at any given time. Making improvements anywhere else in the system won't increase overall performance—only improving the constraint will help. Once you fix that bottleneck, a new constraint will emerge somewhere else in the system.
Real-World Example
Restaurant can seat 100, kitchen can make 50 meals/hour. Kitchen is constraint. Improving service speed won't help. Website: Server handles 1000 requests/sec, database handles 100. Database is constraint. Faster server won't help. Team productivity: Everything waiting on designer. Designer is constraint. More developers won't help.
How to Apply
Map your flow. Identify where work piles up—that's your constraint. Focus ALL improvement there. Ignore everything else (hard but crucial). Once constraint is resolved, find new constraint (it shifted). Repeat forever. Remember: any improvement not at constraint is illusion.