Case 1: Only a deep target is suspected to exist.

Case 2: New evidence reveals shallow target above the originally suspected deep target.

In case 1: Hard to get a hit, even if a major ore body is there. Many holes is the only reasonable plan.

In case 2: Easy to get a hit. One or two holes is a reasonable plan.

In either case the risk that the geological speculation is wrong is significant. in either case existing ore can be missed. But much less likely that a shallow target will be missed than a deep target.

I like Briscoes way of understanding things so I'll take a chance that he's right.