A project management methodology that explicitly deals with this variance: https://en.wikipedia.org/wiki/Critical_chain_project_management https://en.wikipedia

A project management methodology that explicitly deals with this variance: https://en.wikipedia.org/wiki/Critical_chain_project_management https://en.wikipedia.org/wiki/Critical_chain_project_managem... One of the key insights is that estimate-driven planning creates an algorithm that accumulates the delays from late deliveries while being unable to make use of early deliveries.