Nothing is ever built on schedule or within budget.
From the Murphy's law canon, named for the pyramid builder. Flyvbjerg's megaproject data gives it an empirical form: over budget, over time, under benefit, consistently.
In practice
- A kitchen extension quoted at eleven weeks and £40,000 finishes in nineteen weeks at £58,000, and both parties describe this as normal.
- A software migration scoped for one quarter runs into the third, and each individual delay was reasonable.