1. A method comprising: defining a tree structure having a plurality of levels and a plurality of nodes in each of the levels, wherein each of the nodes is interconnected with at least one of a node above or at least two nodes below in the tree structure, and each node defines respective values for a set of electrical stimulation parameters, wherein one of the electrical stimulation parameters comprises a combination of electrodes with which stimulation is delivered to a patient; defining, with a processor, a first program path through the tree structure along a series of the interconnected nodes for which efficacy of stimulation therapy delivered according to the stimulation parameters defined by the nodes exceeds a threshold level; and defining, with the processor, a second program path through the tree structure based on information regarding an operation of the electrodes.