I've only read your post and with not much background on MAK but...

I've only read your post and with not much background on MAK but with a backgound in mining I would say:

(Diamond) drill core is cut up for assaying during exploration and resource estimation stages. This leads to JORC compliant resource estimate if the orebody hangs together i.e. targeting grade and geology. Not enough core is left for metallurgical testing.

Further drilling is required for feasability studies purely for metallurgical test work. This identifies how the ore will go through the mill and the ore characteristics are examined i.e. lump vs fines % etc.

If the deposit was drilled out with RC drilling technique then it is prudent to follow up with diamond holes for met testing also.