Try harder instructions are known to improve performance in a variety of basic cognitive and motor tasks. A signature finding is a reduction of response times, sometimes (but not always) at the expense of overall accuracy. Such try harder effects are typically conceptualized in terms of a transient recruitment of spare cognitive capacity. Here, we test whether try harder instructions may also improve accuracy in a situation without substantial time constraints. To overcome limitations of accuracy measures derived from dichotomous right/wrong tasks, we resorted to assessing dart throwing performance. Participants were instructed to target the bulls eye throughout the experiment. In some mini-blocks, they were instructed to try harder. Additionally, we asessed a control group without any try harder instructions. Overall, results revealed a lack of try harder effects on accuracy, suggesting that while spare mental capacity can be recruited to improve temporal aspects of task processing, a corresponding increase of task focus does not in the same way help to improve response precision.