I think this has been posted before, but it's worth reading again:

Detour Gold takes the cautious route to mine development

"... they delayed delivering BBA’s feasibility study results by three months to conduct third-party reviews"

"Delaying a new project is never a popular decision, but the payback can be worth it if it is done in the early stages"

"We wanted to make sure that our consultants removed the maximum amount of risk possible from the project, and it was the reviewers' job to cross-check that"

"Beaudoin is convinced that many other projects would benefit from the added risk-mitigation provided by a robust audit approach but singles out low-grade deposits as especially in need of the added certainty."