Actually the ROV method is for a more realistic present day valuation of very long term projects combined with fluctuating metal prices - so you are half right.
What I am trying to say, Teck or any operator, would prefer a project that can operate in some of the worst of markets without losing money and having to shut down. DL said just as much in an interview last year ( or was it longer lol!). A project with a low IRR is much better if the project can stay open and break even in poor economic times. Starting and stoping a mine with metal price cycles is difficult and expensive and can cost an operation much of its labour force if they chose to get more consistent paychecks elsewhere.