Looking for schedule success?
Easy! Loosen the coupling!
Remember the "shift right" phenomenom in scheduling?
If two or more events are tightly coupled to a milestone -- meaning no slack -- then a slip of any event pushes the milestone, to wit: shift to the rightAnd, the risk is exponential with the number of events:
The risk of two events is the risk-squared (where risk is probability of success)What's a project manager to do?
Two risks of 80% success each are about 64% likely as a simultaneous pair
Answer: schedule loosely (add buffers to one or more events). This is the main take away in the "Critical Chain" concept, but it's also a fundamental principle in system engineering
- Shock absorbers are needed between critical parts that require some independence of action
No better example of this is in the management of subcontractors that are not captive to your project. They often march to their own drum, putting their interests first. And, why not?
For project success (scheduling being an important success parameter), when dealing with subcontractors, loosen the coupling! Buffer everything they are supposed to do -- if you can. You'll be less disappointed.
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