How large is the local region of influence for a 5DOF interpolation model? Another way of phrasing this question is: how many GBs are necessary to sample in the space to obtain a model that's accurate enough? NN distances give context to these questions: if 50 000 GBs are randomly sampled, then on average, these GBs are (2.6479 ± 0.2254)°a part from their NN. In the context of correlation lengths of ∼7-8°(Section 3.2.1), a random set of at least ∼10 000 GBs is required to reach a reasonable goal of half the correlation length (i.e. to have a reasonably performing structure-property model). By contrast, A set of 388 randomly sampled GBs will yield average NN distances of ∼7.5°. The fact that this is approximately the same as the correlation lengths derived in this work suggest that this size of dataset is far too small. We demonstrate this via an example.