Methods and systems for improving mineral resource exploration and resource classification efficiency are provided herein. The generation and iterative, dynamic improvement of drill plans for sampling a target volume using drill holes is described. Methods and systems for the development and optimization of drill plans are able to accommodate a wide variety of constraints and targets, providing drill plans which aim to minimize the amount of explorative drilling while substantially converting unclassified sub-volumes, and in particular high-desirability sub-volumes, of the target volume to a specified or desired level while attempting to maximize targeted resource conversion efficiency. Resulting drill plans may provide a proposed collection of drill holes, defined in 3D space, penetrating the target volume which sufficiently sample a target volume while remaining within one or more specified constraints.