“Variability” comes up in almost every supply chain conversation I have with clients.
And it almost always points outside the business — things like variability in supplier lead times or shifts in customer demand.
That explanation is not wrong. But it is incomplete.
What we often do not realise is that a significant share of the variability most supply chains are buffering against was generated inside the business.
- Sales teams submit forecasts they know are inflated because the system rewards volume and punishes misses.
- Promotions get confirmed in the planning meeting two weeks after the production decision has already been made. Product launches shift by a month.
- The S&OP number that went into the plan was a negotiated consensus, not a modelled probability.
Every one of those is an internal decision, a process failure, or a behaviour the business tolerates.
This is variability created by incentives, timing, and governance. None of that is in any supplier lead time.
But it shows up in safety stock. It shows up in expediting costs. It shows up in the write-down at the end of the quarter when the launch slipped and the inventory did not.
The typical response is: better forecasting tools, tighter supplier contracts, or more safety stock.
All external fixes for an internal problem.
The harder question is: how much of the variability in your supply chain is a consequence of decisions your own teams are making?
Most organisations do not ask about it. Not because the answer is unknown. Because the answer is uncomfortable.
You cannot buffer your way out of a problem your own process is creating.