The acquisition of new motor skills engages rich neural processes that are still not fully characterized. Behaviorally, learning of a new skill (e.g., the ability to tie up shoelaces) involves two seemingly independent components: (1) the selection of successful heuristics in the form of high-level strategies that efficiently solve the task at hand, and (2) the gradual increase in motor proficiency associated with faster, smoother, and more precise movements. While motor heuristics and motor proficiency both play a significant role in skill learning, it is still unknown how they are orchestrated at the neural level within the motor cortex. One hypothesis is that both aspects of learning might result from a systematic evolution of the “planning horizon”, i.e., how far ahead in time movements are being planned at the start of each attempt. Here, we seek to investigate this hypothesis in the context of an “unconstrained” motor learning task in monkeys. The task requires animals to use a hand-controlled cursor to hit a fixed set of visual targets as quickly as possible in an unprescribed order. Behavioral analyses reveal that monkeys’ performance in this task improve over weeks through a combination of high-level heuristics and motor proficiency. Ongoing analyses of motor cortical activity recorded during the task are attempting to decipher the neural mechanisms at play during the learning process. In particular, our working hypothesis is that systematic population-level changes of preparatory activity in a dedicated “planning subspace” might jointly underlie adjustments of strategies and refinement of motor execution.