Attaining a high level of proficiency in speaking a second language (L2) is a formidable challenge, particularly in many English as a foreign language (EFL) settings, such as Taiwan. In such environments, students often encounter limited opportunities for English-speaking practice within formal classroom settings due to the prevalence of form-focused instruction. Nonetheless, certain students manage to achieve elevated levels of proficiency. This exploratory investigation aims to uncover the strategies employed by such learners beyond formal classroom instruction and identify key factors contributing to high proficiency. Individual studies have underscored the importance of metacognitive knowledge, metacognitive strategies, and practice in L2 learning. To explore how these elements operate synergistically to facilitate self-regulated learning of L2 speaking ability, this exploratory study constructs a model, Metacognitive Practice Speaking Strategies (MPSSs), to delineate their interconnections. Semi-structured interviews were conducted with 18 Taiwanese students, aged 15-25. By comparing the use of MPSSs among speakers of different proficiency levels, key factors contributing to high proficiency are identified. It communicates that the strategy use of high proficiency speakers aligns with established theories of second language (L2) speaking. Given that they received no instruction on these theories, their strategies were presumably guided by task beliefs developed from their initial, use-focused education. Alongside their strategic knowledge, these beliefs led them to perform use-focused MPSSs. The study's context shares similarities with numerous EFL contexts, making the findings broadly applicable to a wide range of L2 learners.