One way to encourage performance and persistence in STEM fields is to have students write about the utility value (UV) or personal relevance of course topics to their life. This intervention has been shown to increase engagement and performance in introductory courses. However, questions remain about the longevity of the effects and how best to implement the intervention in terms of dosage and timing. We tested a UV intervention in the first semester of a 2-semester introductory biology sequence. For each of 3 units across the semester, students (N = 577) were randomly assigned to receive either a UV writing assignment, in which they explained why course material was useful to them personally, or a control assignment, in which they summarized course material. This fully crossed design tested the effect of UV dosage level (0, 1, 2, or 3 UV assignments) as well as the effect of timing (e.g., UV first, control first). We found that students exposed to any dosage of UV earned higher grades in the course, were more likely to enroll in the second course of the biology sequence, and were less likely to abandon their STEM major than students who did not receive any UV assignments. In terms of timing, students with a history of poor performance benefitted from writing a UV essay in the beginning of the semester, whereas higher-performing students benefitted from a UV essay at the end of the semester. Recommendations for practice are discussed.