Nominal sample intervals are 3 m which can result in smoothing...

Nominal sample intervals are 3 m which can result in smoothing of the grade, combined with geological interpretation between drill intervals can limit the ore envelope.
Increasing the drill and sample density usually results in more clarity of where high and low grade regions are. The previous MRE didn't have as much information to go on, so intersected grade will be averaged across wider areas. If inverse distance is used, it can be worse, but if kriging is used for the model the results are better, but still only as accurate as the data allows.

Basically the higher the resolution, the better the grade but the lower the tonnes. That's why it's important to include drilling further afield in each MRE update so that you can have higher grades AND more tonnes. Hopefully. Please. For the love of God, please let there be more tonnes...