The variogram drives interpolation weights and influences classification. Errors here propagate into every downstream number.
Domains
Variograms are modelled per homogeneous domain. Mixing mineralisation styles produces a smoothed model with unpredictable errors.
Anisotropy and nugget
Anisotropy directions should agree with the geology; nugget and ranges with what the data support.
Validation
Swath plots, mean comparisons and production reconciliation are a required part of the report.