This paper examines the degrees to which college students can engage independently in digital learning using their dead times and aims to explore the optimal pedagogical intervention and/or support to be provided for boosting their autonomy and self-efficacy, based on qualitative data. The software instrument used for this study is Testing-Learning-Training (TLT) developed for Japanese learners and the participants are college students majoring nursing, with their motivation for learning English reasonably high. However, findings revealed their limited time engagement in digital learning; which may require a structural intervention. Taken into account the socio-psychological studies on autonomy in the framework of self-determination theory and self-efficacy leading to self-regulated learning, the optimal intervention and/or support for engaging students in independent digital learning are discussed.