One of the frequently noticed issues in language- learning ITSs is over-restricting the learning domain, both horizontally and vertically. Horizontal domain restriction refers to a system’s tendency to focus on a single linguistic skill (listening, reading, speaking and writing) or form (grammar, vocabulary) rather than a combination of them. Including a whole range of skills/forms or even all of them into the ITS would be more in line with the nature of language learning, which emphasizes the integration of both productive and receptive skills, visual and auditory input, written and spoken output, form and communicative competence, etc [27]. Conversely, vertical domain restriction refers to the inability of an ITS to cater for learners with different levels of language proficiency (e.g., CEFR proficiency levels A1 – C2), which decreases the number of potential system users and, consequently, system’s (potential) financial value. We maintain that a possible solution and a more sensible approach would be to offer learning content designed for a wide range of skills, forms and ability levels, and use the knowledge about the learner, kept by the ITS, to detect which skills/forms are needed by each learner. Moreover, learner data should be used to identify the learner’s current level of proficiency, offer learning materials that are appropriate for the identified level, and decide when the new level of proficiency has been reached.