Hmmmm sounds like you have more of an issues with bulk samples than with head grades.
If I understand your main point, it is that the grades at the start of the process matter little because it is more important what you can produce profitably at the end of the process that matters.
Ultimately, when all is said and done (process fully implemented and fine tuned) you are right but the potential with higher grades is so much higher than lower grades that at the early stages of a mining operation, grade has to be considered one to be one of the most important factors in the likelihood of the success (profitability) of a mine. It's one of the best forward indicators of the possible degree of success of a beginning mining operation. There are just so many more ways to make a buck from high grades than there is from low grades.
Not to say that grades are a be all and end all as I have certainly seen high grade operations that have been duds as producers for a variety of reasons. But head grade and the change in head grade over time is a very telling story.
JFF7
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