While you may be correct, geology is not as consistent as your post suggests. It (Geol) is a bit like the disclaimer one sees on financial products "past results do not guarantee future results".
At Fraser Range there is likely to be variable top cover (0-100 or so metres) consisting of:
transported sand etc (<=20m?) over the top of
variably weathered bedrock ((<=~100m)an area where many economic minerals are moved around by ground water etc - some are removed others concentrated). At Nova there were geochemical signatures, including cobalt, which encouraged Sirius to drill deeper.
Below this "cover" is fresh rock where economic mineralisation can be found (rarely) at any depth. Without some geochemistry, geophysics or prior drilling to target under the cover deep drilling on its own stands very little chance of success. A bit like buying Lotto where if you don't have a ticket there is no chance of winning but you rarely do.
The Fraser Range IMO has been a very difficult exploration target. The nickel boom of the 70's came up with sniffs. Sirius got "lucky" with Nova-B, in hindsight given many millions of dollars has been spent since without much more than technical successes (AFAIK). Highly experience explorationists are being supported by management and hopefully will get rewarded for their efforts.
Reminds me of my early days of working in the Thompson Nickel Belt of Canada. Lots of targets under lakes, swamps and glacial overburden but not many have since turned into mines. Some did and paid for way more than the exploration. Still interested in exploration geology after many fun years cracking rocks.
