Getting the most out of spacing involves figuring out the right amount of time to space. This is important because better recall is positively correlated with the amount of spacing up until a certain point, after which recall begins to worsen with longer spacing intervals. The optimal amount of spacing depends on the RI, with longer RIs corresponding to longer periods in between spacing. Demonstrating this is an example from a study by Cependa et al., who showed that "the optimal spacing gap for a one-week test delay is about one day, while the optimal spacing gap for a one year test delay is about three weeks"