In learning journals, prompts were shown to increase self-regulated learning processes effectively. As studies on effects of long-term prompting are sparse, this study investigates the effects of prompting cognitive and metacognitive self-regulation strategies short-term and long-term in learning journals on learners' strategy use, self-efficacy, and learning outcome. Therefore, 74 university students kept a weekly learning journal as follow-up course work over a period of eight weeks. All students' learning journals included prompts for a short-term period, half of the students were prompted long-term. While self-efficacy was assessed via self-reports, strategy use was measured with self-reports and qualitative data from the learning journals. Learning outcomes were assessed via course exams. Short-term prompting increased self-reported cognitive and metacognitive strategy use, and the quantity of cognitive strategy use. Yet, it did not affect self-efficacy, which predicted the learning outcome. Irrespective whether prompting continued or not, self-reported cognitive and metacognitive strategy use, and self-efficacy decreased. Qualitative data indicate that the quantity of learners' cognitive strategy use kept stable irrespective of the condition. The results indicate that short-term prompting activates cognitive and metacognitive strategy use. Long-term prompting in learning journals had no effect on strategy use, self-efficacy, and performance. Future research should investigate possible enhancers of long-term prompting like feedback, adaptive prompts or additional support.