Until about ten years ago, painting the Forth Bridge was a handy metaphor for a never-ending task*. The idea seemed to be that the bridge was so massive that they no sooner finished than they had to start again. But if you put yourself in the position of an employer with a big maintenance requirement, you realise that the correct number of people to hire is exactly the number who can work on it continuously. Anything more is wasteful.
What's this got to do with mineral reserves? The No-Breakfast doomsayers need to perform a similar thought inversion. If they did, they would realise that the economical amount of any resource is the smallest you can safely get away with. It applies to minerals, components for factories, stocks in supermarkets and painters.
* I understand they've now developed a paint that lasts so long that continuous painting is no longer necessary. Where are we going to find a new metaphor?