Recent research has suggested that students prefer restudying over retrieval practice when learning difficult materials, despite the latter being a more effective learning strategy. The current study investigated whether an instructional intervention can improve the use of retrieval practice for both easy and difficult materials. In Experiment 1, after initial learning of each item, participants rated their perceived mental effort (PME) and judgment of learning (JOL) for each item. Then, participants chose whether to restudy or take retrieval practice for that item. The results showed that participants chose to take retrieval practice less frequently for difficult items compared to easy ones. Furthermore, participants' ratings of PME and JOL sequentially mediated the relationship between item difficulty and their learning strategy choices. Specifically, difficult items resulted in higher levels of PME, which in turn led to lower JOL, ultimately reducing the likelihood of choosing retrieval practice. In Experiment 2, half of the participants received an instructional intervention, which revealed that while students prefer restudying for difficult items, retrieval practice benefits both easy and difficult items in long-term retention. The remaining half did not receive such intervention and were designated as the control group. The results indicated that, compared to the control group, students who received the intervention increased the odds of choosing retrieval practice for both types of materials after the intervention. The findings of this study suggest that students can be supported to use retrieval practice regardless of item difficulty.